WorldWideScience

Sample records for superthermal collision energies

  1. Head-on collision of two dust ion acoustic solitary waves in a weakly relativistic multicomponent superthermal plasma

    Science.gov (United States)

    Saini, N. S.; Singh, Kuldeep

    2016-10-01

    A head-on collision between two dust ion acoustic solitary waves (DIASWs) travelling in the opposite direction in a weakly relativistic plasma composed of four distinct particle populations, namely, weakly relativistic ion fluid, superthermal electrons as well as positrons, and immobile dust, is investigated. By employing extended Poincaré-Lighthill-Kuo method, two Korteweg-de Vries (KdV) equations are derived. The analytical phase shift after a head-on collision of two dust ion acoustic (DIA) solitary waves is also obtained. The combined effects of relativistic factor (β), electron to positron temperature ratio (α), ion to electron temperature ratio (σ), positron to electron density ratio (P), dust density ratio (d), and superthermality of electrons as well as positrons (via κ) on the phase shifts are numerically studied. All these physical parameters have also changed the potential amplitude and the width of colliding solitary waves. It is found that the presence of superthermal electrons as well as positrons and dust grains has emphatic influence on the phase shifts and potential pulse profiles of compressive DIA solitons. Our results are general and may be helpful in understanding a head-on collision between two DIASWs in astrophysical and laboratory plasmas, especially the interaction of pulsar relativistic winds with supernova ejecta that produces the superthermal particles and relativistic ions.

  2. Head on collision of multi-solitons in an electron-positron-ion plasma having superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Kaushik, E-mail: kaushikbolpur@rediffmail.com [Beluti M. K. M. High School, P.O. Beluti, Birbhum, West Bengal 731301 (India); Chatterjee, Prasanta, E-mail: prasantachatterjee1@rediffmail.com; Roychoudhury, Rajkumar [Department of Mathematics, Siksha Bhavana Visva Bharati, Santiniketan 731235 (India)

    2014-10-15

    The head-on collision and overtaking collision of four solitons in a plasma comprising superthermal electrons, cold ions, and Boltzmann distributed positrons are investigated using the extended Poincare-Lighthill-Kuo (PLK) together with Hirota's method. PLK method yields two separate Korteweg-de Vries (KdV) equations where solitons obtained from any KdV equation move along a direction opposite to that of solitons obtained from the other KdV equation, While Hirota's method gives multi-soliton solution for each KdV equation all of which move along the same direction where the fastest moving soliton eventually overtakes the other ones. We have considered here two soliton solutions obtained from Hirota's method. Phase shifts acquired by each soliton due to both head-on collision and overtaking collision are calculated analytically.

  3. Making More-Complex Molecules Using Superthermal Atom/Molecule Collisions

    Science.gov (United States)

    Shortt, Brian; Chutjian, Ara; Orient, Otto

    2008-01-01

    A method of making more-complex molecules from simpler ones has emerged as a by-product of an experimental study in outer-space atom/surface collision physics. The subject of the study was the formation of CO2 molecules as a result of impingement of O atoms at controlled kinetic energies upon cold surfaces onto which CO molecules had been adsorbed. In this study, the O/CO system served as a laboratory model, not only for the formation of CO2 but also for the formation of other compounds through impingement of rapidly moving atoms upon molecules adsorbed on such cold interstellar surfaces as those of dust grains or comets. By contributing to the formation of increasingly complex molecules, including organic ones, this study and related other studies may eventually contribute to understanding of the origins of life.

  4. On the superthermal UCN production

    Energy Technology Data Exchange (ETDEWEB)

    Yoshiki, Hajime [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    In 1992, the production of ultracold neutrons (UCN) by means of superthermal method predicted by Golub and Pendlebury was verified quantitatively by changing incident cold neutron wavelength to observe the maximum of UCN production at a certain wavelength. At this wavelength, the dispersion curve of superfluid liquid helium and the energy momentum curve of a free neutron cross, and the energy and momentum of incident neutrons can be converted entirely to those of produced phonons, thus the neutrons with infinitesimal energy are left, which are UCN. It was learned that the calculation by Cohen and Feynman is correct, and now the rate of UCN production per unit time can be calculated. The comparison of this with other methods is discussed. The heat that would be produced in liquid helium if it was exposed to a cold neutron field was calculated. The proposed set of the circulation pumps for {sup 3}He combined with a new heat exchanger gives the answer to the problem. Two main objectives for getting a strong UCN source are the precise determination of neutron lifetime and the search for the electric dipole moment of neutrons. The e.d.m. measurement machine integrated with refrigeration parts is shown. Preliminary measurement was done for the three-layer high permeability shield. (K.I.)

  5. Mechanical Energy Changes in Perfectly Inelastic Collisions

    Science.gov (United States)

    Mungan, Carl E.

    2013-01-01

    Suppose a block of mass "m"[subscript 1] traveling at speed "v"[subscript 1] makes a one-dimensional perfectly inelastic collision with another block of mass "m"[subscript 2]. What else does one need to know to calculate the fraction of the mechanical energy that is dissipated in the collision? (Contains 1 figure.)

  6. Novel energy sharing collisions of multicomponent solitons

    Indian Academy of Sciences (India)

    T Kanna; K Sakkaravarthi; M Vijayajayanthi

    2015-11-01

    In this paper, we discuss the fascinating energy sharing collisions of multicomponent solitons in certain incoherently coupled and coherently coupled nonlinear Schrödinger-type equations arising in the context of nonlinear optics.

  7. Non-steady-state transport of superthermal electrons in the plasmasphere

    Science.gov (United States)

    Khazanov, George V.; Liemohn, Michael W.; Gombosi, Tamas I.; Nagy, Andrew F.

    1993-01-01

    Numerical solutions to the time-dependent kinetic equation, which describes the transport of superthermal electrons in the splasmasphere between the two conjugate ionospheres, are presented. The model calculates the distribution function as a function of time, field-aligned distance, energy, and pitch-angle. The processes of refilling, depleting, and establishing steady-state conditions of superthermal electrons in the plasmasphere are discussed.

  8. High energy density in multisoliton collisions

    Science.gov (United States)

    Saadatmand, Danial; Dmitriev, Sergey V.; Kevrekidis, Panayotis G.

    2015-09-01

    Solitons are very effective in transporting energy over great distances and collisions between them can produce high energy density spots of relevance to phase transformations, energy localization and defect formation among others. It is then important to study how energy density accumulation scales in multisoliton collisions. In this study, we demonstrate that the maximal energy density that can be achieved in collision of N slowly moving kinks and antikinks in the integrable sine-Gordon field, remarkably, is proportional to N2, while the total energy of the system is proportional to N . This maximal energy density can be achieved only if the difference between the number of colliding kinks and antikinks is minimal, i.e., is equal to 0 for even N and 1 for odd N and if the pattern involves an alternating array of kinks and antikinks. Interestingly, for odd (even) N the maximal energy density appears in the form of potential (kinetic) energy, while kinetic (potential) energy is equal to zero. The results of the present study rely on the analysis of the exact multisoliton solutions for N =1 ,2 , and 3 and on the numerical simulation results for N =4 ,5 ,6 , and 7. The effect of weak Hamiltonian and non-Hamiltonian perturbations on the maximal energy density in multikink collisions is also discussed as well as that of the collision relative phase. Based on these results one can speculate that the soliton collisions in the sine-Gordon field can, in principle, controllably produce very high energy density. This can have important consequences for many physical phenomena described by the Klein-Gordon equations.

  9. Photons from nuclear collisions at RHIC energies

    CERN Document Server

    Gale, Charles; Frodermann, Evan; Heinz, Ulrich

    2008-01-01

    We model the hot and dense strongly interacting mater produced in high energy heavy ion collisions using relativistic hydrodynamics. Several different sources of real photons produced during these collisions are considered and their relative importance is assessed. We include contributions from QCD jets, which are allowed to loose and gain energy as they proceed through the hot matter. This is treated within the AMY formalism. We obtain photon spectra, R_{AA}, and v_2 in agreement with measurements performed by the PHENIX collaboration.

  10. Drift and ion acoustic wave driven vortices with superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, QAU Campus, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, QAU Campus, 44000 Islamabad (Pakistan)

    2012-08-15

    Linear and nonlinear analysis of coupled drift and acoustic mode is presented in an inhomogeneous electron-ion plasma with {kappa}-distributed electrons. A linear dispersion relation is found which shows that the phase speed of both the drift wave and the ion acoustic wave decreases in the presence of superthermal electrons. Several limiting cases are also discussed. In the nonlinear regime, stationary solutions in the form of dipolar and monopolar vortices are obtained. It is shown that the condition for the boundedness of the solution implies that the speed of drift wave driven vortices reduces with increase in superthermality effect. Ignoring density inhomogeniety, it is investigated that the lower and upper limits on the speed of the ion acoustic driven vortices spread with the inclusion of high energy electrons. The importance of results with reference to space plasmas is also pointed out.

  11. High energy photon-photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.J. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    1994-07-01

    The collisions of high energy photons produced at a electron-positron collider provide a comprehensive laboratory for testing QCD, electroweak interactions and extensions of the standard model. The luminosity and energy of the colliding photons produced by back-scattering laser beams is expected to be comparable to that of the primary e{sup +}e{sup {minus}} collisions. In this overview, we shall focus on tests of electroweak theory in photon-photon annihilation, particularly {gamma}{gamma} {yields} W{sup +}W{sup {minus}}, {gamma}{gamma} {yields} Higgs bosons, and higher-order loop processes, such as {gamma}{gamma} {yields} {gamma}{gamma}, Z{gamma} and ZZ. Since each photon can be resolved into a W{sup +}W{sup minus} pair, high energy photon-photon collisions can also provide a remarkably background-free laboratory for studying WW collisions and annihilation. We also review high energy {gamma}{gamma} tests of quantum chromodynamics, such as the scaling of the photon structure function, t{bar t} production, mini-jet processes, and diffractive reactions.

  12. Horndeski/Galileon in High Energy Collisions

    CERN Document Server

    Latosh, B N

    2016-01-01

    Horndeski/Galileons may be considered as a proper generalization of General Relativity in high energy regime. Thus one may search for manifestation of Galileons interaction in collision experiments. In this paper we give arguments supporting this thesis. Galileon scalar field do not interact with matter via Standard Model interactions, we discuss a mechanism that allows Galileons to have influence on particle collisions. We give reasons to narrow the whole class of Horndeski/Galileons models to one particular term - John term from Fab Four subclass - for this particular issue. We were able to establish the constraint on the model coupling constant.

  13. Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1980-01-01

    A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.

  14. Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1980-01-01

    A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.

  15. Absorbed Energy in Ship Collisions and Grounding

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    is that the absorbed energy does not depend on the arrangement of the structure, the material properties, and the damage mode.The purpose of the present paper is to establish a new simple relation between the absorbed energy and the destroyed material volume, which can be used as a design tool for analysis of ship......Minorsky's well-known empirical formula, which relates the absorbed energy to the destroyed material volume, has been widely used in analyses of high energy collision and grounding accidents for nearly 40 years. The advantage of the method is its apparent simplcity. Obviously, its drawback...

  16. High energy particle collisions near black holes

    Directory of Open Access Journals (Sweden)

    Zaslavskii O. B.

    2016-01-01

    Full Text Available If two geodesic particles collide near a rotating black hole, their energy in the centre of mass frame Ec.m. can become unbound under certain conditions (the so-called BSW effect. The special role is played here by so-called critical geodesics when one of particles has fine-tuned energy and angular momentum. The nature of geodesics reveals itself also in fate of the debris after collisions. One of particles moving to a remote observer is necessarily near-critical. We discuss, when such a collision can give rise not only unboud Ec.m. but also unbound Killing energy E (so-called super-Penrose process.

  17. Noncommutative QED Threshold Energy versus Optimum Collision Energy

    Institute of Scientific and Technical Information of China (English)

    SHENG Zheng-Mao; FU Yong-Ming; YU Hai-Bo

    2005-01-01

    @@ M(o)11er scattering and Bhabha scattering on noncommutative (NC) space-time is restudied. It is shown that the NC correction of scattering sections is not monotonic enhancement with total energy of colliding electrons, that there is an optimum collision energy to perform the greatest NC correction.

  18. On the fully nonlinear acoustic waves in a plasma with positrons beam impact and superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Ali Shan, S. [Theoretical Plasma Physics Division, PINSTECH, Nilore, 44000 Islamabad (Pakistan); National Centre For Physics (NCP), Shahdra Valley Road, 44000 Islamabad (Pakistan); Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad (Pakistan); El-Tantawy, S. A.; Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said 42521 (Egypt)

    2013-08-15

    Arbitrary amplitude ion-acoustic waves in an unmagnetized plasma consisting of cold positive ions, superthermal electrons, and positrons beam are reported. The basic set of fluid equations is reduced to an energy-balance like equation. The latter is numerically analyzed to examine the existence regions for solitary and shock waves. It is found that only solitary waves can propagate, however, the model cannot support shocks. The effects of superthermality and beam parameters (via, positrons concentration and streaming velocity) on the existence region, as well as solitary wave profile have been discussed.

  19. Ion-acoustic solitons, double layers and rogue waves in plasma having superthermal electrons

    Science.gov (United States)

    Singh Saini, Nareshpal

    2016-07-01

    Most of the space and astrophysical plasmas contain different type of charged particles with non-Maxwellian velocity distributions (e.g., nonthermal, superthermal, Tsallis ). These distributions are commonly found in the auroral region of the Earth's magnetosphere, planetary magnetosphere, solar and stellar coronas, solar wind, etc. The observations from various satellite missions have confirmed the presence of superthermal particles in space and astrophysical environments. Over the last many years, there have been a much interest in studying the different kind of properties of the electrostatic nonlinear excitations (solitons, double layers, rogue waves etc.) in a multi-component plasmas in the presence of superthermal particles. It has been analyzed that superthermal distributions are more appropriate than Maxwellian distribution for the modeling of space data. It is interesting to study the dynamics of various kinds of solitary waves, Double layers, Shocks etc. in varieties of plasma systems containing different kind of species obeying Lorentzian (kappa-type)/Tsallis distribution. In this talk, I have focused on the study of large amplitude IA solitary structures (bipolar solitary structures, double layers etc.), modulational instability and rogue waves in multicomponent plasmas. The Sagdeev potential method has been employed to setup an energy balance equation, from which we have studied the characteristics of large amplitude solitary waves under the influence of superthermality of charged particles and other plasma parameters. The critical Mach number has been determined, above which solitary structures are observed and its variation with superthermality of electrons and other parameters has also been discussed. Double layers have also been discussed. Multiple scale reductive perturbation method has been employed to derive NLS equation. From the different kind of solutions of this equation, amplitude modulation of envelope solitons and rogue waves have been

  20. Collision geometry and particle production in high energy heavy ion collision experiments

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-Ping; ZHOU Dai-Mei; HUANG Rui-Dian; CAI Xu

    2008-01-01

    An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented.This paper includes four parts:1)Theoretical predictions of quarkgluon plasma and introduction for high energy heavy ion collision experiments.2)Experimental status on collision geometry.3)Experimental status on particle production.4)Conclusion and outlook for research status of soft physics in LHC/ALICE.

  1. Some Intensive and Extensive Quantities in High-Energy Collisions

    CERN Document Server

    Tawfik, A

    2013-01-01

    We review the evolution of some statistical and thermodynamical quantities measured in difference sizes of high-energy collisions at different energies. We differentiate between intensive and extensive quantities and discuss the importance of their distinguishability in characterizing possible critical phenomena of nuclear collisions at various energies with different initial conditions.

  2. Arbitrary amplitude kinetic Alfven solitary waves in two temperature electron superthermal plasma

    Science.gov (United States)

    Singh, Manpreet; Singh Saini, Nareshpal; Ghai, Yashika

    2016-07-01

    Through various satellite missions it is observed that superthermal velocity distribution for particles is more appropriate for describing space and astrophysical plasmas. So it is appropriate to use superthermal distribution, which in the limiting case when spectral index κ is very large ( i.e. κ→∞), shifts to Maxwellian distribution. Two temperature electron plasmas have been observed in auroral regions by FAST satellite mission, and also by GEOTAIL and POLAR satellite in the magnetosphere. Kinetic Alfven waves arise when finite Larmor radius effect modifies the dispersion relation or characteristic perpendicular wavelength is comparable to electron inertial length. We have studied the kinetic Alfven waves (KAWs) in a plasma comprising of positively charged ions, superthermal hot electrons and Maxwellian distributed cold electrons. Sagdeev pseudo-potential has been employed to derive an energy balance equation. The critical Mach number has been determined from the expression of Sagdeev pseudo-potential to see the existence of solitary structures. It is observed that sub-Alfvenic compressive solitons and super-Alfvenic rarefactive solitons exist in this plasma model. It is also observed that various parameters such as superthermality of hot electrons, relative concentration of cold and hot electron species, Mach number, plasma beta, ion to cold electron temperature ratio and ion to hot electron temperature ratio have significant effect on the amplitude and width of the KAWs. Findings of this investigation may be useful to understand the dynamics of coherent non-linear structures (i.e. KAWs) in space and astrophysical plasmas.

  3. Bubble chambers in high energy hadron collisions (and vice versa)

    Energy Technology Data Exchange (ETDEWEB)

    Kittel, W. (Dept. Exp. High Energy Physics, Univ. of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen (Netherlands))

    1994-07-01

    The contribution of bubble chambers to the field of high energy hadron collisions during the last 20 years is reviewed and results are compared to those from other types of collisions and to expectations from models based on the quark-parton content of the respective hadrons. ((orig.))

  4. On the Global Ship Hull Bending Energy in Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Y.

    2004-01-01

    During ship collisions part of the kinetic energy of the involved vessels prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can be stored in elastic...... absorbed by the struck ship normally is small and varies from 1 to 6 % of the energy released for crushing. The energy stored as elastic global hull girder vibrations depends on the ship mass, the local stiffness of the side structure, and of the position of contact. The results also show that for highly...... hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non trivial part of the energy released for structural deformation during the collision can be absorbed as elastic energy in global...

  5. On the global ship hull bending energy in ship collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Yujie

    2009-01-01

    be stored in elastic hull vibrations during a ship collision. When a ship side is strengthened in order to improve the crashworthiness it has been argued in the scientific literature that a non-trivial part of the energy released for structural deformation during the collision can be absorbed as elastic...... energy absorbed by the struck ship normally is small and varies from 1 to 6% of the energy released for crushing. The energy stored as elastic global hull girder vibrations depends on the ship mass, the local stiffness of the side structure, and of the position of contact. The results also show......During ship collisions part of the kinetic energy of the involved vessels immediately prior to contact is absorbed as energy dissipated by crushing of the hull structures, by friction and by elastic energy. The purpose of this report is to present an estimate of the elastic energy that can...

  6. High energy nuclear collisions: Theory overview

    Indian Academy of Sciences (India)

    R J Fries

    2010-08-01

    We review some basic concepts of relativistic heavy-ion physics and discuss our understanding of some key results from the experimental program at the relativistic heavy-ion collider (RHIC). We focus in particular on the early time dynamics of nuclear collisions, some result from lattice QCD, hard probes and photons.

  7. Theory of low energy collisions; Theorie des collisions a basse energie

    Energy Technology Data Exchange (ETDEWEB)

    Sparenberg, J.M. [Universite Libre de Bruxelles, Bruxelles (Belgium)

    2007-07-01

    The basic notions of low-energy quantum scattering theory are introduced (cross sections, phase shifts, resonances,... ), in particular for positively-charged particles, in view of nuclear physics applications. An introduction to the reaction-matrix (or R-matrix) method is then proposed, as a tool to both solve the Schroedinger equation describing collisions and fit experimental data phenomenologically. Most results are established without proof but with a particular emphasis on their intuitive understanding and their possible analogs in classical mechanics. Several choices are made consequently: (i) the text starts with a detailed reminder of classical scattering theory, (ii) the concepts are first introduced in ideal theoretical cases before going to the more complicated formalism allowing the description of realistic experimental situations, (iii) a single example is used throughout nearly the whole text, (iv) all concepts are established for the elastic scattering of spinless particles, with only a brief mention of their multichannel generalization at the end of the text. (author)

  8. Microscopic descriptions of high-energy heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bodmer, A.R.

    1977-01-01

    The essentials of the equation-of-motion (EOM) approach are given and some of its significant and interesting results are described. A framework for the theoretical description of high-energy heavy-ion (HE-HI) collisions is presented; specifically included are a critical assessment of various approaches--EOM calculations, Boltzmann equations/cascade calculations, and hydrodynamics--their relationships and their respective domains of applicability, if any, to HE-HI collisions. 11 figures, 3 tables. (RWR)

  9. Heavy Quark and Quarkonium Transport in High Energy Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Kai [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Institute for Theoretical Physics, Johann Wolfgang Goethe-University, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main (Germany); Dai, Wei [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China); Xu, Nu [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Zhuang, Pengfei [Physics Department, Tsinghua University and Collaborative Innovation Center of Quantum Matter, Beijing 100084 (China)

    2016-12-15

    The strong interaction between heavy quarks and the quark gluon plasma makes the open and hidden charm hadrons be sensitive probes of the deconfinement phase transition in high energy nuclear collisions. Both the cold and hot nuclear matter effects change with the colliding energy and significantly influence the heavy quark and charmonium yield and their transverse momentum distributions. The ratio of averaged quarkonium transverse momentum square and the elliptic flow reveal the nature of the QCD medium created in heavy ion collisions at SPS, RHIC and LHC energies.

  10. Interaction of ion-acoustic solitons with electron beam in warm plasmas with superthermal electrons

    CERN Document Server

    Esfandyari-Kalejahi, A R

    2012-01-01

    Propagation of ion-acoustic solitary waves (IASWs) is studied using the hydrodynamic equations coupled with the Poisson equation in a warm plasma consisting of adiabatic ions and superthermal (Kappa distributed) electrons in presence of an electron-beam component. In the linear limit, the dispersion relation for ion-acoustic (IA) waves is obtained by linearizing of basic equations. On the other hand, in the nonlinear analysis, an energy-balance like equation involving Sagdeev's pseudo-potential is derived in order to investigate arbitrary amplitude IA solitons. The Mach number range is determined in which, propagation and characteristics of IA solitons are analyzed both parametrically and numerically. The variation of amplitude and width of electrostatic (ES) excitations as a result of superthermality (via) and also the physical parameters (ion temperature, soliton speed, electron-beam density and electron-beam velocity) are examined. A typical interaction between IASWs and the electron-beam in plasma is conf...

  11. On the rogue wave propagation in ion pair superthermal plasma

    Energy Technology Data Exchange (ETDEWEB)

    Abdelwahed, H. G., E-mail: hgomaa-eg@yahoo.com, E-mail: hgomaa-eg@mans.edu.eg; Zahran, M. A. [Physics Department, College of Sciences and Humanities Studies Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj (Saudi Arabia); Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt); El-Shewy, E. K., E-mail: emadshewy@yahoo.com; Elwakil, S. A. [Theoretical Physics Group, Physics Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2016-02-15

    Effects of superthermal electron on the features of nonlinear acoustic waves in unmagnetized collisionless ion pair plasma with superthermal electrons have been examined. The system equations are reduced in the form of the nonlinear Schrodinger equation. The rogue wave characteristics dependences on the ionic density ratio (ν = n{sub –0}/n{sub +0}), ionic mass ratio (Q = m{sub +}/m{sub −}), and superthermality index (κ) are investigated. It is worth mentioning that the results present in this work could be applicable in the Earth's ionosphere plasmas.

  12. Physics of Nuclear Collisions at High Energy

    Energy Technology Data Exchange (ETDEWEB)

    Hwa, Rudolph C. [Univ. of Oregon, Eugene, OR (United States)

    2012-05-01

    A wide range of problems has been investigated in the research program during the period of this grant. Although the major effort has been in the subject of heavy-ion collisions, we have also studied problems in biological and other physical systems. The method of analysis used in reducing complex data in multiparticle production to simple descriptions can also be applied to the study of complex systems of very different nature. Phase transition is an important phenomenon in many areas of physics, and for heavy-ion collisions we study the fluctuations of multiplicities at the critical point. Human brain activities as revealed in EEG also involve fluctuations in time series, and we have found that our experience enables us to find the appropriate quantification of the fluctuations in ways that can differentiate stroke and normal subjects. The main topic that characterizes the research at Oregon in heavy-ion collisions is the recombination model for the treatment of the hadronization process. We have avoided the hydrodynamical model partly because there is already a large community engaged in it, but more significantly we have found the assumption of rapid thermalization unconvincing. Recent results in studying LHC physics lead us to provide more evidence that shower partons are very important even at low p_T, but are ignored by hydro. It is not easy to work in an environment where the conventional wisdom regards our approach as being incorrect because it does not adhere to the standard paradigm. But that is just what a vibrant research community needs: unconventional approach may find evidences that can challenge the orthodoxy. An example is the usual belief that elliptic flow in fluid dynamics gives rise to azimuthal anisotropy. We claim that it is only sufficient but not necessary. With more data from LHC and more independent thinkers working on the subject what is sufficient as a theory may turn out to be incorrect in reality. Another area of investigation that

  13. Dimesoatoms production in high energy collisions

    CERN Document Server

    Afanasyev, L; Voskresenskaya, O

    2016-01-01

    The production of two meson electromagnetic bound states and free meson pairs $\\pi^+\\pi^-$, $K^+K^-$, $\\pi^+ K^{\\mp}$ in relativistic collisions has been considered. It was shown that making use of the exact Coulomb wave function for dimesoatom (DMA) allows one to calculate the yield of any nS state with desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained.

  14. ``Thermal'' and ``superthermal'' two-class structure of the personal income distribution

    Science.gov (United States)

    Yakovenko, Victor

    2005-03-01

    In Ref. [1] we proposed an analogy between the thermal Boltzmann-Gibbs probability distribution of energy in physics and the probability distribution of money in economics in statistical equilibrium. In Ref. [2] we find that the probability distribution of personal income in the USA has a well-defined two-class structure. The majority of population (97-99%) belongs to the lower class characterized by the exponential Boltzmann-Gibbs (``thermal'') distribution, whereas the upper class (1-3% of population) has a Pareto power-law (``superthermal'') distribution. By analyzing the income data for 1983--2001 from IRS, we show that the ``thermal'' part is stationary in time, save for a gradual increase of the effective temperature, whereas the nonequilibrium ``superthermal'' tail swells and shrinks following the stock market. We discuss the concept of equilibrium inequality in a society, based on the principle of maximal entropy, and quantitatively show that it applies to the majority of the US population. [] [1] A. Dragulescu and V. M. Yakovenko, ``Statistical mechanics of money'', Eur. Phys. J. B 17, 723--729 (2000). [cond-mat/0001432] [] [2] A. C. Silva and V. M. Yakovenko, ``Temporal evolution of the `thermal' and `superthermal' income classes in the USA during 1983--2001'', accepted to Europhysics Letters. [cond- mat/0406385

  15. Isotope analysis in central heavy ion collisions at intermediate energies

    Science.gov (United States)

    Geraci, E.; Abbondanno, U.; Bardelli, L.; Barlini, S.; Bini, M.; Bruno, M.; Cannata, F.; Casini, G.; Chiari, M.; D'Agostino, M.; de Sanctis, J.; Giussani, A.; Gramegna, F.; Kravchuk, V. L.; Lanchais, A. L.; Marini, P.; Moroni, A.; Nannini, A.; Olmi, A.; Ordine, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Vannini, G.; Nucl-Ex Collaboration

    2007-11-01

    Symmetry energy is a key quantity in the study of the equation of state of asymmetric nuclear matter. Heavy ion collisions at low and intermediate energies, performed at Laboratori Nazionali di Legnaro and Laboratori Nazionali del Sud, can be used to extract information on the symmetry energy coefficient Csym, which is currently poorly known but relevant both for astrophysics and for deeper knowledge of the structure of exotic nuclei.

  16. Direct Experimental Evidence of Nonequilibrium Energy Sharing in Dissipative Collisions

    Science.gov (United States)

    Casini, G.; Maurenzig, P. R.; Olmi, A.; Bini, M.; Calamai, S.; Meucci, F.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Gobbi, A.; Hildenbrand, K. D.

    1997-02-01

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and energy-time-of-flight measurements, respectively, for the direct and reverse collisions of 100Mo with 120Sn at 14.1A MeV. Direct experimental evidence of the correlation of energy sharing with net mass transfer and model-independent results on the evolution of the average excitation from equal-energy to equal-temperature partition are presented.

  17. Isotope analysis in central heavy ion collisions at intermediate energies

    CERN Document Server

    Geraci, E; Bardelli, L; Barlini, S; Bini, M; Bruno, M; Cannata, F; Casini, G; Chiari, M; D'Agostino, M; De Sanctis, J; Giussani, A; Gramegna, F; Kravchuk, V L; Lanchais, A L; Marini, P; Moroni, A; Nannini, A; Olmi, A; Ordine, A; Pasquali, G; Piantelli, S; Poggi, G; Vannini, G

    2006-01-01

    Symmetry energy is a key quantity in the study of the equation of state of asymmetric nuclear matter. Heavy ion collisions at low and intermediate energies, performed at Laboratori Nazionali di Legnaro and Laboratori Nazionali del Sud, can be used to extract information on the symmetry energy coefficient Csym, which is currently poorly known but relevant both for astrophysics and for structure of exotic nuclei.

  18. Beam energy scan with asymmetric collision at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alessi, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Beebe, E. [Brookhaven National Lab. (BNL), Upton, NY (United States); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brennan, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brown, K. A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Butler, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Connolly, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); D Ottavio, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Drees, K. A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Gu, X. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hao, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Harvey, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hayes, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hulsart, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ingrassia, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Jamilkowski, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Laster, J. S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Litvinenko, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mapes, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marr, G. J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); McIntyre, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Michnoff, R. [Brookhaven National Lab. (BNL), Upton, NY (United States); Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Montag, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Morris, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Naylor, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Nemesure, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Pinayev, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ranjbar, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Raparia, D. [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roser, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Sampson, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Sandberg, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Schoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Severino, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Shrey, T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Smith, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tepikian, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Than, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States); thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States); Tuozzolo, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wang, G. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zaltsman, A. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zeno, K. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhang, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Zhang, W. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2016-11-15

    A beam energy scan of deuteron-gold collision, with center-of-mass energy at 19.6, 39, 62.4 and 200.7 GeV/n, was performed at the Relativistic Heavy Ion Collider in 2016 to study the threshold for quark-gluon plasma (QGP) production. The lattice, RF, stochastic cooling and other subsystems were in different configurations for the various energies. The operational challenges changed with every new energy. The operational experience at each energy, the operation performance, highlights and lessons of the beam energy scan are reviewed in this report.

  19. Avian collision risk models for wind energy impact assessments

    Energy Technology Data Exchange (ETDEWEB)

    Masden, E.A., E-mail: elizabeth.masden@uhi.ac.uk [Environmental Research Institute, North Highland College-UHI, University of the Highlands and Islands, Ormlie Road, Thurso, Caithness KW14 7EE (United Kingdom); Cook, A.S.C.P. [British Trust for Ornithology, The Nunnery, Thetford IP24 2PU (United Kingdom)

    2016-01-15

    With the increasing global development of wind energy, collision risk models (CRMs) are routinely used to assess the potential impacts of wind turbines on birds. We reviewed and compared the avian collision risk models currently available in the scientific literature, exploring aspects such as the calculation of a collision probability, inclusion of stationary components e.g. the tower, angle of approach and uncertainty. 10 models were cited in the literature and of these, all included a probability of collision of a single bird colliding with a wind turbine during passage through the rotor swept area, and the majority included a measure of the number of birds at risk. 7 out of the 10 models calculated the probability of birds colliding, whilst the remainder used a constant. We identified four approaches to calculate the probability of collision and these were used by others. 6 of the 10 models were deterministic and included the most frequently used models in the UK, with only 4 including variation or uncertainty in some way, the most recent using Bayesian methods. Despite their appeal, CRMs have their limitations and can be ‘data hungry’ as well as assuming much about bird movement and behaviour. As data become available, these assumptions should be tested to ensure that CRMs are functioning to adequately answer the questions posed by the wind energy sector. - Highlights: • We highlighted ten models available to assess avian collision risk. • Only 4 of the models included variability or uncertainty. • Collision risk models have limitations and can be ‘data hungry’. • It is vital that the most appropriate model is used for a given task.

  20. Dileptons in high-energy heavy-ion collisions

    Indian Academy of Sciences (India)

    Ralf Rapp

    2003-04-01

    The current status of our understanding of dilepton production in ultra-relativistic heavyion collisions is discussed with special emphasis on signals from the (approach towards) chirally restored and deconfined phases. In particular, recent results of the CERN-SPS low-energy runs are compared to model predictions and interpreted. Prospects for RHIC experiments are given.

  1. Direct photon production in high-energy nuclear collisions

    NARCIS (Netherlands)

    Peitzmann, T.

    2016-01-01

    Direct photons have always been considered a promising probe for the very early phases of high-energy nuclear collisions. Prompt photons reveal information about the initial state and its possible modifications in nuclei. In this context they should be one of the best probes for effects of gluon sat

  2. Correlations and fluctuations in high energy heavy ion collision experiments

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dai-Mei; WANG Ya-Ping; WEI Li-Hua; CAI Xu

    2008-01-01

    An overview of research status of soft physics in high energy heavy-ion collision experiments and recent experimental results are presented.The experimental status on fluctuations and correlations has been reviewed and the outlook for research status of soft physics in LHC/ALICE has been introduced in this paper.

  3. Probing the nuclear symmetry energy with heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    De Filippo E.

    2015-01-01

    Full Text Available Heavy ion collisions (HIC have been widely used to extract the parametrization of symmetry energy term of nuclear equation of state as a function of barionic density. HIC in fact are a unique tool in terrestrial laboratories to explore the symmetry energy around the saturation density (ρ0 = 0.16fm−3 from sub-saturation densities (Fermi energies towards compressed nuclear matter (ρ > 2 − 3ρ0 that can be reached at relativistic energies, as a function of different conditions of temperature, mass asymmetry and isospin. One of the main study at present is to reach a coherent description of EOS of asymmetric nuclear matter from heavy ion collisions of stable and exotic nuclei, nuclear structure studies and astrophysical observations. In this work an overview of the current status of the research is shortly reviewed together with new perspectives aimed to reduce the present experimental and theoretical uncertainties.

  4. Two models with rescattering for high energy heavy ion collisions

    Science.gov (United States)

    Bøggild, H.; Hansen, Ole; Humanic, T. J.

    2006-12-01

    The effects of hadronic rescattering in high energy relativistic Au+Au collisions are studied using two very different models to describe the early stages of the collision. One model is based on a hadronic thermal picture and the other on a superposition of parton-parton collisions. Operationally, the output hadrons from each of these models are used as input to a hadronic rescattering calculation. The results of the rescattering calculations from each model are then compared with rapidity and transverse momentum distributions from the BNL Relativistic Heavy Ion Collider BRAHMS experiment. In spite of the different points of view of the two models of the initial stage, after rescattering, the observed differences between the models are mostly “washed out” and both models give observables that agree roughly with each other and with experimental data.

  5. Binary cluster collision dynamics and minimum energy conformations

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, Francisco [Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle (Germany); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile); Rogan, José; Valdivia, J.A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile); Varas, A. [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Nano-Bio Spectroscopy Group, ETSF Scientific Development Centre, Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián (Spain); Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y Nanotecnología, CEDENNA, Avenida Ecuador 3493, Santiago (Chile)

    2013-10-15

    The collision dynamics of one Ag or Cu atom impinging on a Au{sub 12} cluster is investigated by means of DFT molecular dynamics. Our results show that the experimentally confirmed 2D to 3D transition of Au{sub 12}→Au{sub 13} is mostly preserved by the resulting planar Au{sub 12}Ag and Au{sub 12}Cu minimum energy clusters, which is quite remarkable in view of the excess energy, well larger than the 2D–3D potential barrier height. The process is accompanied by a large s−d hybridization and charge transfer from Au to Ag or Cu. The dynamics of the collision process mainly yields fusion of projectile and target, however scattering and cluster fragmentation also occur for large energies and large impact parameters. While Ag projectiles favor fragmentation, Cu favors scattering due to its smaller mass. The projectile size does not play a major role in favoring the fragmentation or scattering channels. By comparing our collision results with those obtained by an unbiased minimum energy search of 4483 Au{sub 12}Ag and 4483 Au{sub 12}Cu configurations obtained phenomenologically, we find that there is an extra bonus: without increase of computer time collisions yield the planar lower energy structures that are not feasible to obtain using semi-classical potentials. In fact, we conclude that phenomenological potentials do not even provide adequate seeds for the search of global energy minima for planar structures. Since the fabrication of nanoclusters is mainly achieved by synthesis or laser ablation, the set of local minima configurations we provide here, and their distribution as a function of energy, are more relevant than the global minimum to analyze experimental results obtained at finite temperatures, and is consistent with the dynamical coexistence of 2D and 3D liquid Au clusters conformations obtained previously.

  6. Mutual neutralization at low collision energies: the power of imaging

    Science.gov (United States)

    Vassantachart, April K.; Romano, Shalynn L.; Martin, Merl F.; Andrianarijaona, Vola M.; O'Connor, Aodh; Urbain, Xavier

    2014-05-01

    Mutual neutralization studies are generally limited to energies above a few eV, and do not specify the electronic state of the products, merely indicating a band of principal quantum numbers based on time-of-flight intervals. We upgraded our merged beam set-up to reach meV collision energies, and incorporated three-dimensional product imaging. Besides providing clear coincidence signals, this technique gives unambiguous identification of the electronic states of the products. Knowing their angular distribution at the different collision energies allows absolute cross sections to be retrieved. Results for the H+/H-andHe+/H- systems will be presented, providing detailed branching ratios for non-degenerate channels. This research is supported by the Fund for Scientific Research - FNRS through IISN Grant No. 4.4504.10, and the National Science Foundation through Grant No. PHY-106887.

  7. Direct Experimental Evidence of Nonequilibrium Energy Sharing in Dissipative Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Casini, G.; Maurenzig, P.; Olmi, A.; Bini, M.; Calamai, S.; Meucci, F.; Pasquali, G.; Poggi, G.; Stefanini, A. [Istituto Nazionale di Fisica Nucleare and Universita di Firenze, I--50125 Florence (Italy); Gobbi, A.; Hildenbrand, K. [Gesellschaft fuer Schwerionenforschung, D--64291 Darmstadt (Germany)

    1997-02-01

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and energy{endash}time-of-flight measurements, respectively, for the direct and reverse collisions of {sup 100}Mo with {sup 120}Sn at 14.1AMeV. Direct experimental evidence of the correlation of energy sharing with net mass transfer and model-independent results on the evolution of the average excitation from equal-energy to equal-temperature partition are presented. {copyright} {ital 1997} {ital The American Physical Society}

  8. Investigation of Rare Particle Production in High Energy Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    None

    1999-09-02

    Our program is an investigation of the hadronization process through measurement of rare particle production in high energy nuclear interactions. Such collisions of heavy nuclei provide an environment similar in energy density to the conditions in the Big Bang. We are currently involved in two major experiments to study this environment, E896 at the AGS and STAR at RHIC. We have completed our physics running of E896, a search for the H dibaryon and measurement of hyperon production in AuAu collisions, and are in the process of analyzing the data. We have produced the electronics and software for the STAR trigger and will begin to use these tools to search for anti-nuclei and strange hadrons when RHIC turns on later this year.

  9. Electromagnetic radiation from nuclear collisions at RHIC energies

    CERN Document Server

    Turbide, Simon; Frodermann, Evan; Heinz, Ulrich

    2008-01-01

    The hot and dense strongly interacting matter created in collisions of heavy nuclei at RHIC energies is modeled with relativistic hydrodynamics, and the spectra of real and virtual photons produced at mid-rapidity in these events are calculated. Several different sources are considered, and their relative importance is compared. Specifically, we include jet fragmentation, jet-plasma interactions, the emission of radiation from the thermal medium and from primordial hard collisions. Our calculations consistently take into account jet energy loss, as evaluated in the AMY formalism. We obtain results for the spectra, the nuclear modification factor (R_AA), and the azimuthal anisotropy (v_2) that agree with the photon measurements performed by the PHENIX collaboration at RHIC.

  10. Disoriented Chiral Condensates in High-Energy Nuclear Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Randrup, Jorgen

    2000-10-18

    This brief lecture series discusses how our current understanding of chiral symmetry may be tested more globally in high-energy nuclear collisions by suitable extraction of pionic observables. After briefly recalling the general features of chiral symmetry, we focus on the SU(2) linear sigma model and show how a semi-classical mean-field treatment makes it possible to calculate its statistical properties, including the chiral phase diagram. Subsequently, we consider scenarios of relevance to high-energy collisions and discuss the features of the ensuing non-equilibrium dynamics and the associated characteristic signals. Finally, we illustrate how the presence of vacuum fluctuations or the inclusion of strangeness may affect the results quantitatively.

  11. Chimera microscopic approach to heavy ion collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Lukasik, J.; Majka, Z. [Uniwersytet Jagiellonski, Cracow (Poland). Inst. Fizyki

    1993-12-01

    A microscopic model based on a molecular dynamics concept is presented. The model simulates some quantum effects and thus enables studies of large fermionic systems. It was devised to investigate the dynamics of heavy ion collision at intermediate energies. The model was applied to study an early phase of the {sup 84}Kr+{sup 159}Tb reaction at 45 MeV/nucleon. (author). 30 refs, 9 figs.

  12. Azimuthal Distributions in Intermediate Energy Heavy-Ion Collisions

    Science.gov (United States)

    Wilson, William Kenneth

    The azimuthal distributions of light particles (Z = 1,2) with respect to the entrance channel reaction plane are investigated with a view towards characterizing the modes of collective motion in intermediate energy heavy -ion collisions. A new technique for reaction plane determination from the distribution of light particles produced in a collision is developed and applied to Ar+V data. The data were acquired using the MSU 4pi Array, a new 215 element large solid angle detector system. At a beam energy of 35 MeV/nucleon, light charged particles are found to exhibit an enhanced emission in the reaction plane which increases with the mass of the detected particle. As the beam energy is increased to 100 MeV/nucleon, the anisotropy nearly vanishes, providing clues to the dynamics of these reactions in a transitional energy regime. The observed anisotropy contains signatures of two distinct modes of collective motion: attractive mean field deflection, and rotation of the fused system. A microscopic calculation based on mean-field mediated interactions plus nucleon-nucleon collisions reproduces both forms of collective motion and their associated azimuthal distributions. The calculation also suggests that the anisotropy due to mean -field deflection is established during the initial stages of the collision. The nature of the nuclear mean-field is further explored using data taken by the 4pi Array for peripheral 50 MeV/nucleon C induced reactions on C and Au targets. Although projectile fragments in grazing collisions are positively deflected by the coulomb force, a specific set of protons are found to be simultaneously attractively deflected by the mean-field towards the opposite side of the reaction plane. This direct observation of attractive mean field deflection supports aspects of the interpretation of the Ar+V data. Lastly, the experimental results are summarized and the potential for extracting more information about the dynamics of heavy-ion collisions using

  13. Spectroscopic diagnostics of superthermal electrons with high-number harmonic EC radiation in tokamak reactor plasmas

    Directory of Open Access Journals (Sweden)

    Minashin P.V.

    2015-01-01

    Full Text Available A method of spectroscopic diagnostics of the average perpendicular-to-magnetic-field momentum of the superthermal component of the electron velocity distribution (EVD, based on the high-number-harmonic electron cyclotron (EC radiation, is suggested for nuclear fusion-reactor plasmas under condition of a strong auxiliary heating (e.g. in tokamak DEMO, a next step after tokamak ITER. The method is based on solving an inverse problem for reconstruction of the EVD in parallel and perpendicular-to-magnetic-field components of electron momentum at high and moderate energies responsible for the emission of the high-number-harmonic EC radiation.

  14. Avalanche Phenomenon of Superthermal Electrons Measured by SDD with New SPHA during ECRH

    Institute of Scientific and Technical Information of China (English)

    YANG Jin-Wei; CHEN Liao-Yuan; RAO Jun; YANG Qing-Wei; ZHANG Yi-Po; LIAO Min; HU Li-Qun; LI Xu; SONG Xian-Ying; LIN Shi-Yao; LI Yong-Ge; LUO Cui-Wen

    2008-01-01

    @@ Two high performance silicon drift detectors(SDD)are installed at the equatorial port with z=0 and z=-16.4cm on HL-2A tokamak,respectively.These SDDs combine with the new and non-conventional software pulse height analyser(SPHA)successfully developed more recently by us to measure the time evolution of soft x-rays spectra,the thermal and superthermal electron temperatures.The high-quality three-dimensional figure of time evolution for soft x-rays energy spectra is easily obtained by combination of a new SPHA and computer.

  15. High energy collisions of particles inside ergosphere: general approach

    CERN Document Server

    Zaslavskii, O B

    2013-01-01

    We show that recent observation made in Grib and Pavlov, arXiv:1301.0698 for the Kerr black hole is valid in the general case of rotating axially symmetric metric. Namely, collision of two particles in the ergosphere leads to indefinite growth of the energy in the centre of mass frame, provided the angular momentum of one of two particles is negative and increases without limit for a fixed energy at infinity. General approach enabled us to elucidate, why the role of the ergosphere in this process is crucial.

  16. Charged Particle, Photon Multiplicity, and Transverse Energy Production in High-Energy Heavy-Ion Collisions

    Directory of Open Access Journals (Sweden)

    Raghunath Sahoo

    2015-01-01

    Full Text Available We review the charged particle and photon multiplicities and transverse energy production in heavy-ion collisions starting from few GeV to TeV energies. The experimental results of pseudorapidity distribution of charged particles and photons at different collision energies and centralities are discussed. We also discuss the hypothesis of limiting fragmentation and expansion dynamics using the Landau hydrodynamics and the underlying physics. Meanwhile, we present the estimation of initial energy density multiplied with formation time as a function of different collision energies and centralities. In the end, the transverse energy per charged particle in connection with the chemical freeze-out criteria is discussed. We invoke various models and phenomenological arguments to interpret and characterize the fireball created in heavy-ion collisions. This review overall provides a scope to understand the heavy-ion collision data and a possible formation of a deconfined phase of partons via the global observables like charged particles, photons, and the transverse energy measurement.

  17. Transverse Energy in nucleus-nucleus collisions: A review

    Energy Technology Data Exchange (ETDEWEB)

    Tincknell, M.

    1988-11-15

    The status of Transverse Energy (E/sub T/) in relativistic nucleus-nucleus collisions at the Brookhaven AGS and the CERN SPS is reviewed. The definition of E/sub T/ and its physical significance are discussed. The basic techniques and limitations of the experimental measurements are presented. The acceptances of the major experiments to be discussed are shown, along with remarks about their idiosyncrasies. The data demonstrate that the nuclear geometry of colliding spheres primarily determines the shapes of the observed spectra. Careful account of the acceptances is crucial to comparing and interpreting results. It is concluded that nuclear stopping power is high, and that the amount of energy deposited into the interaction volume is increasing with beam energy even at SPS energies. The energy densities believed to be obtained at the SPS are close to the critical values predicted for the onset of a quark-gluon plasma. 25 refs., 8 figs.

  18. Pion dynamics in nuclear collisions at SIS Energies

    Energy Technology Data Exchange (ETDEWEB)

    Senger, P. (Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany) Frankfurt Univ. (Germany) Marburg Univ. (Germany) Cracow Univ. (Poland)); KaoS Collaboration

    1993-01-01

    Heavy ion collisions at intermediate energies provide the unique possibility of investigating the properties of hot and compressed nuclear matter in the laboratory. According to microscopic transport calculations a baryon density of 2-3 [rho][sub o] can be reached for about 5 x 10[sup -23]s in a volume of approximately 100 fm[sup 3]. In order to extract information on nuclear matter properties from such a collision, the effects of the reaction dynamics on the experimental observables has to be understood. The most important dissipative process in a nuclear reaction around 1.0 GeV/u bombarding energy is the resonance excitation of nucleons, such as N N [yields] N [Delta] and N N [yields] N N*. The abundant baryonic resonances play a key role in the subthreshold production of particles like kaons, etas and antiprotons. With high probability these resonances decay by emitting pions as a reminder of a transient stage of hadronic matter. Therefore, pion production is a crucial test for theoretical models aiming to describe the reaction mechanism and subthreshold particle production. The high pion abundancy permits exploration of the space-time evolution of a nuclear collision. (author).

  19. Hipse: an event generator for nuclear collisions at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Lacroix, D.; Van Lauwe, A.; Durand, D

    2003-11-01

    An event generator, HIPSE (Heavy-Ion Phase-Space Exploration), dedicated to the description of nuclear collisions in the intermediate energy range is presented. Based on the sudden approximation and on geometrical hypothesis, it can conveniently simulate heavy-ion interactions at all impact parameters and thus can constitute a valuable tool for the understanding of processes such as neck emission or multifragmentation in peripheral or/and central collisions. After a detailed description of the ingredients of the model, first comparisons with experimental data collected by the INDRA collaboration are shown. Special emphasis is put on the kinematical characteristics of fragments and light particles observed at all impact parameters for Xe+Sn reactions at 25 and 50 MeV/u and Ni + Ni at 82 MeV/u. (authors)

  20. Diphoton production in high-energy p+A collisions

    CERN Document Server

    Kovner, Alex

    2014-01-01

    We consider semi-inclusive diphoton+jet and inclusive diphoton production in high-energy proton-nucleus collisions, treating the target nucleus as a Color-Glass-Condensate while the projectile proton in the parton model. We obtain the prompt diphoton production cross-section in terms of fragmentation and direct contributions. The fragmentation part is given in terms of single-photon and double-photon fragmentation functions. We study prompt, direct and fragmentation diphoton correlations in p+p and p+A collisions at the LHC, and show that at low values of transverse momenta of the produced photon pair, these correlations are sensitive to saturation effects. We show that back-to-back (de)-correlations in prompt diphoton production are stronger in fragmentation part than in the direct one.

  1. Diphoton production in high-energy p+A collisions

    Science.gov (United States)

    Kovner, Alex; Rezaeian, Amir H.

    2014-07-01

    We consider semi-inclusive diphoton +jet and inclusive diphoton production in high-energy proton-nucleus collisions, treating the target nucleus as a color-glass condensate and the projectile proton in the parton model. We obtain the prompt diphoton production cross section in terms of fragmentation and direct contributions. The fragmentation part is given in terms of single-photon and double-photon fragmentation functions. We study prompt, direct, and fragmentation diphoton correlations in p +p and p +A collisions at the LHC and show that at low values of transverse momenta of the produced photon pair these correlations are sensitive to saturation effects. We show that back-to-back (de)correlations in prompt diphoton production are stronger in the fragmentation part than in the direct one.

  2. Characteristics of New-type Energy Absorber for Vehicle Collision

    Institute of Scientific and Technical Information of China (English)

    XU Qing-xin; SHEN Rong-ying; ZHOU Hai-ting

    2008-01-01

    A new type energy absorber was introduced, which is composed of thousands of thin ring plates with different diameters. Because it can switch the impact to thousands of shearing actions among thin ring plates inside the absorber, the impact energy is decentralized and dissipated gradually, the impact acting time is extended and the peak of acceleration is reduced obviously. Numerical simulations by finite element method (FEM) coupled with smoothed particle hydrodynamics (SPH) method were preformed to predict the energy absorption characteristics. Energy absorption ability with different impact velocities was studied and the effects of thickness and material of ring plates were discussed. The sled crash test was carried out to validate the result of simulations. The new type absorber is effective for collision that impact velocity is lower than 40 km/h.

  3. Effects of Photon Absorption in High Energy Heavy Ion Collisions

    Science.gov (United States)

    Winchell, Joshua; Somanathan, Sidharth; Fries, Ranier

    2014-09-01

    Photons are an important probe of the hot and dense nuclear matter created in high-energy collisions of nuclei at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). Since the mean free path of photons is larger than the size of the fireball of nuclear matter, final state interactions of photons are usually neglected. In light of recent tension between theoretical calculations and data from RHIC and LHC, we study the effect of reabsorption of photons on elliptic flow v2 and on the nuclear modification factor RAA. We consider photons emitted in primary hard collisions and thermal photons from quark-gluon plasma and hot hadron gas. We use the jet-quenching code PPM to simulate the propagation of those photons in a fireball of quark-gluon plasma and hot hadron gas created by collisions of heavy nuclei. For the absorption cross-sections we consider three different approaches: (a) Compton and pair production processes calculated by us in a static approximation, (b) the photon damping rates calculated by Thoma (1995), and (c) absorption rates derived from a recent photon calculation by van Hees et al.

  4. Isotope Effects in Low Energy Ion-Atom Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Havener, Charles C [ORNL; Seely, D. G. [Albion College; Thomas, J. D. [University of Toledo, Toledo, OH; Kvale, Thomas Jay [University of Toledo, Toledo, OH

    2009-01-01

    Isotope effects for charge transfer processes have recently received increased attention. The ion-atom merged-beams apparatus at Oak Ridge National Laboratory is used to measure charge transfer for low energy collisions of multi-charged ions with H and D and is therefore well suited to investigate isotope effects. The apparatus has been relocated and upgraded to accept high velocity beams from the 250 kV High Voltage Platform at the Multi-Charged Ion Research Facility. The intense higher velocity multi-charged ion beams allow, for the first time, measurements with both H and D from keV/u down to meV/u collision energies in the center-of-mass frame. When charge transfer occurs at relatively large inter-nuclear distances (via radial couplings) the ion-induced dipole attraction can lead to trajectory effects, causing differences in the charge transfer cross sections for H and D. A strong isotope effect (nearly a factor of two) has been observed in the cross section for Si4+ + H(D) below 0.1 eV/u. However, little or no difference is observed for N2+ + H(D). Recently, strong effects have been predicted for the fundamental system He2+ + H(D,T) at collision energies below 200 eV/u where charge transfer occurs primarily through united-atom rotational coupling. We are currently exploring systems where rotational coupling is important and isotopic differences in the cross section can be observed.

  5. Energy and angular momentum sharing in dissipative collisions

    CERN Document Server

    Casini, G; Calamai, S; Laforest, R; Maurenzig, P R; Olmi, A; Pasquali, G; Piantelli, S; Poggi, G; Saint-Laurent, F; Steckmeyer, J C; Stefanini, A A; Taccetti, N

    2000-01-01

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using the information from both the heavy fragments and the light charged particles. The ratio of Hydrogen and Helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer.

  6. Energy and angular momentum sharing in dissipative collisions

    Science.gov (United States)

    Casini, G.; Bini, M.; Calamai, S.; Laforest, R.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Saint-Laurent, F.; Steckmeyer, J. C.; Stefanini, A. A.; Taccetti, N.

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 93Nb and 116Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using information from both the heavy fragments and the light charged particles. The ratio of hydrogen and helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer.

  7. Energy and angular momentum sharing in dissipative collisions

    Energy Technology Data Exchange (ETDEWEB)

    Casini, G.; Bini, M.; Calamai, S.; Maurenzig, P.R.; Olmi, A.; Pasquali, G.; Piantelli, S.; Poggi, G.; Stefanini, A.A.; Taccetti, N. [Istituto Nazionale di Fisica Nucleare, Florence (Italy); Laforest, R.; Steckmeyer, J.C. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Saint-Laurent, F. [Grand Accelerateur National d' Ions Lourds (GANIL), 14 - Caen (France)

    2000-12-01

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of {sup 93}Nb and {sup 116}Sn at 25 AMeV. Light charged particles have also been measured in coincidence with the heavy fragments. Direct experimental evidence of the correlation of energy-sharing with net mass transfer has been found using information from both the heavy fragments and the light charged particles. The ratio of hydrogen and helium multiplicities points to a further correlation of angular momentum sharing with net mass transfer. (orig.)

  8. A new physical phenomenon in ultra-high energy collisions

    Directory of Open Access Journals (Sweden)

    Allen Jeffrey D.

    2013-06-01

    Full Text Available We show that combining the published Pierre Auger Observatory measurements of the longitudinal and lateral properties of UHE atmospheric showers, points to an unforeseen change in the nature of particle interactions at ultrahigh energy. A “toy model” of UHE proton-air interactions is presented which provides the first fully consistent description of air shower observations. It demonstrates that the observed energy dependence of the depth-of-shower-maximum distribution may not indicate a transition to a heavier composition, as commonly assumed. While fundamentally phenomenological, the model is based on considerations of how the normal vacuum of QCD might be vaporized and chiral symmetry restored by the extreme energy densities produced in UHE collisions. Whatever its origin, understanding this unexpected phenomenon opens exciting directions in particle physics and may impact Early Universe cosmology.

  9. Energy Dependence of Multiplicity Fluctuations in Heavy Ion Collisions

    CERN Document Server

    Lungwitz, B; Anticic, T; Baatar, B; Barna, D; Bartke, J; Betev, L; Białkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flier, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Ga´zdzicki, M; Genchev, V; Georgopoulos, G; Gładysz, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Lacey, R; Van Leeuwen, M; Lévai, Peter; Litov, L; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Włodarczyk, Z; Wojtaszek, A; Yoo, I K; Zimányi, J; Lungwitz, Benjamin

    2006-01-01

    The energy dependence of multiplicity fluctuations was studied for the most central $Pb+Pb$ collisions at $20A$, $30A$, $40A$, $80A$ and $158A$ GeV by the NA49 experiment at the CERN SPS. The multiplicity distribution for negatively and positively charged hadrons is significantly narrower than Poisson one for all energies. No significant structure in energy dependence of the scaled variance of multiplicity fluctuations is observed. The measured scaled variance is lower than the one predicted by the grand-canonical formulation of the hadron-resonance gas model. The results for scaled variance are in approximate agreement with the string-hadronic model UrQMD.

  10. Single-collision studies of energy transfer and chemical reaction

    Energy Technology Data Exchange (ETDEWEB)

    Valentini, J.J. [Columbia Univ., New York, NY (United States)

    1993-12-01

    The research focus in this group is state-to-state dynamics of reaction and energy transfer in collisions of free radicals such as H, OH, and CH{sub 3} with H{sub 2}, alkanes, alcohols and other hydrogen-containing molecules. The motivation for the work is the desire to provide a detailed understanding of the chemical dynamics of prototype reactions that are important in the production and utilization of energy sources, most importantly in combustion. The work is primarily experimental, but with an important and growing theoretical/computational component. The focus of this research program is now on reactions in which at least one of the reactants and one of the products is polyatomic. The objective is to determine how the high dimensionality of the reactants and products differentiates such reactions from atom + diatom reactions of the same kinematics and energetics. The experiments use highly time-resolved laser spectroscopic methods to prepare reactant states and analyze the states of the products on a single-collision time scale. The primary spectroscopic tool for product state analysis is coherent anti-Stokes Raman scattering (CARS) spectroscopy. CARS is used because of its generality and because the extraction of quantum state populations from CARS spectra is straightforward. The combination of the generality and easy analysis of CARS makes possible absolute cross section measurements (both state-to-state and total), a particularly valuable capability for characterizing reactive and inelastic collisions. Reactant free radicals are produced by laser photolysis of appropriate precursors. For reactant vibrational excitation stimulated Raman techniques are being developed and implemented.

  11. Multisource thermal model to the transverse momentum spectra in pp collisions at RHIC and LHC energies

    CERN Document Server

    Li, BC; Liu, F; Wen, XJ

    2016-01-01

    In an improved multisource thermal model, we systematically investigate the transverse momentum spectra in pp collisions at high energies ranging from 62.4 GeV to 7 TeV. The results are compared with the experimental data in RHIC and LHC. Based on the collision energy dependence of the source-excitation factors, we estimate the transverse momentum spectra in pp collisions at higher energies, potential future pp colliders operating at 33 and 100 TeV.

  12. Elliptic flow in heavy-ion collisions at NICA energies

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Yu.B. [National Research Centre ' ' Kurchatov Institute' ' (NRC ' ' Kurchatov Institute' ' ), Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation); Soldatov, A.A. [National Research Nuclear University ' ' MEPhI' ' (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2016-08-15

    The transverse-momentum-integrated elliptic flow of charged particles at midrapidity, v{sub 2} (charged), and that of identified hadrons from Au+Au collisions are analyzed in the range of incident energies relevant to the Nuclotron-based Ion Collider Facility (NICA). Simulations are performed within a three-fluid model employing three different equations of state (EoSs): a purely hadronic EoS and two versions of the EoS involving the deconfinement transition-a first-order phase transition and a smooth crossover one. The present simulations demonstrate low sensitivity of v{sub 2} (charged) to the EoS. All considered scenarios equally well reproduce recent STAR data on v{sub 2} (charged) for mid-central Au+Au collisions and properly describe its change of sign at the incident energy decrease below √(s{sub NN}) ∼ 3.5 GeV. The predicted integrated elliptic flow of various species exhibits a stronger dependence on the EoS. A noticeable sensitivity to the EoS is found for anti-protons and, to a lesser extent, for K{sup -} mesons. Presently there are no experimental data that could verify these predictions. Future experiments at NICA could corroborate these findings. (orig.)

  13. Collision of low energy Na+ ion with C60

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The collision-induced reaction of Na+ ion with neutral C6o vapour was investigated at the energy range of 10 to 150 eV. The deposited films were studied via laser desorption time-of-flight mass spectroscopy (TOFMS). The fragment products of C60 with even number of carbon atoms, such as Cn+ (n=58, 56, 54), and adduct products, such as Cn+ (n=62, 64, 66, 68) were obser.vcd in the positively charged TOF mass spectra. The endohedral fullerene ion of Na@C60+ was detected when collision energies are above 20 eV. Besides, no negative endohedral fullerene was detected, the products appearing in positively charged mass spectra were also observed in the negatively charged mass spectra. In addition, a series of products with odd number of carbon atoms, such as Cn- (n=53, 55, 57, 59, 61, 63, 65, 67), also appeared, but the intensities of their signals were not as high as that of even numbered. Finally, it is interesting to find that the deposited films are insoluable in toluene, benzene or water. Their Fourier transform infrared (FTIR) spectra seem like those photopolymerized ones. Some of the reaction schemes are proposed to explain the experimental results.

  14. Eikonal model analysis of elastic hadron collisions at high energies

    CERN Document Server

    Prochazka, Jiri

    2016-01-01

    Elastic collisions of protons at different energies represent main background in studying the structure of fundamental particles at the present. On the basis of standardly used model proposed by West and Yennie the protons have been then interpreted as transparent objects; elastic events have been interpreted as more central than inelastic ones. It will be shown that using eikonal model the protons may be interpreted in agreement with usual ontological conception; elastic processes being more peripheral than inelastic ones. The corresponding results (differing fundamentally from those of WY model) will be presented by analyzing the most ample elastic data set measured at ISR energy of 53 GeV. Detailed analysis of measured differential cross section will be performed and different alternatives of peripheral behavior on the basis of eikonal model will be presented. The impact of recently established electromagnetic form factors on determination of quantities specifying hadron interaction determined from the fit...

  15. Medical radiation dosimetry theory of charged particle collision energy loss

    CERN Document Server

    McParland, Brian J

    2014-01-01

    Accurate radiation dosimetry is a requirement of radiation oncology, diagnostic radiology and nuclear medicine. It is necessary so as to satisfy the needs of patient safety, therapeutic and diagnostic optimisation, and retrospective epidemiological studies of the biological effects resulting from low absorbed doses of ionising radiation. The radiation absorbed dose received by the patient is the ultimate consequence of the transfer of kinetic energy through collisions between energetic charged particles and atoms of the tissue being traversed. Thus, the ability of the medical physicist to both measure and calculate accurately patient dosimetry demands a deep understanding of the physics of charged particle interactions with matter. Interestingly, the physics of charged particle energy loss has an almost exclusively theoretical basis, thus necessitating an advanced theoretical understanding of the subject in order to apply it appropriately to the clinical regime. ​ Each year, about one-third of the worl...

  16. The gluon condensation at high energy hadron collisions

    Directory of Open Access Journals (Sweden)

    Wei Zhu

    2017-03-01

    Full Text Available We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing–antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton–proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron–hadron colliders.

  17. The gluon condensation at high energy hadron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wei, E-mail: weizhu@mail.ecnu.edu.cn [Department of Physics, East China Normal University, Shanghai 200241 (China); Lan, Jiangshan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2017-03-15

    We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing–antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton–proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron–hadron colliders.

  18. Covariance analysis of symmetry energy observables from heavy ion collision

    Directory of Open Access Journals (Sweden)

    Yingxun Zhang

    2015-10-01

    Full Text Available Using covariance analysis, we quantify the correlations between the interaction parameters in a transport model and the observables commonly used to extract information of the Equation of State of Asymmetric Nuclear Matter in experiments. By simulating 124Sn + 124Sn, 124Sn + 112Sn and 112Sn + 112Sn reactions at beam energies of 50 and 120 MeV per nucleon, we have identified that the nucleon effective mass splitting is most strongly correlated to the neutrons and protons yield ratios with high kinetic energy from central collisions especially at high incident energy. The best observable to determine the slope of the symmetry energy, L, at saturation density is the isospin diffusion observable even though the correlation is not very strong (∼0.7. Similar magnitude of correlation but opposite in sign exists for isospin diffusion and nucleon isoscalar effective mass. At 120 MeV/u, the effective mass splitting and the isoscalar effective mass also have opposite correlation for the double n/p and isoscaling p/p yield ratios. By combining data and simulations at different beam energies, it should be possible to place constraints on the slope of symmetry energy (L and effective mass splitting with reasonable uncertainties.

  19. Energy-momentum balance in particle - domain wall perforating collision

    CERN Document Server

    Gal'tsov, D V; Spiirin, P A

    2014-01-01

    We investigate the energy-momentum balance in the perforating collision of a point particle with an infinitely thin planar domain wall within the linearized gravity in arbitrary dimensions. Since the metric of the wall increases with distance, the wall and the particle are never free, and their energy-momentum balance involves not only the instantaneous kinetic momenta, but also the non-local contribution of gravitational stresses. However, careful analysis shows that the stresses can be unambiguously divided between the colliding objects leading to definition of the gravitationally dressed momenta. These take into account for gravity in the same way as the potential energy does in the non-relativistic theory, but our treatment is fully relativistic. Another unusual feature of our problem is the non-vanishing flux of the total energy-momentum tensor through the lateral surface of the world tube. In this case the zero divergence of the energy-momentum tensor does not imply conservation of the total momentum de...

  20. Correlations in Particle Production in Nuclear Collisions at LHC Energies

    CERN Document Server

    Sputowska, Iwona

    New data on forward-backward charged particle correlations and multiplicity uctuations in Pb+Pb collisions at p sNN = 2.76 TeV measured by the ALICE detector at CERN are presented. The analysis focuses on the dependence of (a) the correlation coecient bcorr, (b) the intensive quantity ! and (c) the strongly-intensive quantity as a function of (1) the pseudorapidity gap (2) the centrality of the collision and (3) the width of the centrality bin. The considered observables are studied for Pb+Pb data with two dierent centrality estimators. The centrality selection methods are based on charged particle multiplicity measurement by the ALICE VZERO detector and on determination of energy carried by spectator systems by the Zero Degree Calorimeter. A strong dependence of the measured magnitude of forward-backward correlation (bcorr), and of the size of multiplicity uctuations (!), is observed as a function of the ap- plied centrality estimator and as a function of the size of centrality window. A dominant eect on ...

  1. Energy dependence of resonance production in relativistic heavy ion collisions

    CERN Document Server

    Shao, Feng-lan; Wang, Rui-qin; Zhang, Mao-sheng

    2016-01-01

    The production of hadronic resonances $K^{*}(892)$, $\\phi(1020)$, $\\Sigma^{*}(1385)$, and $\\Xi^{*}(1530)$ in central AA collisions at $\\sqrt{s_{NN}}=$ 17.3, 200, and 2760 GeV are systematically studied. The direct production of these resonances at system hadronization are described by the quark combination model and the effects of hadron multiple-scattering stage are dealt with by a ultra-relativistic quantum molecular dynamics model (UrQMD). We study the contribution of these two production sources to final observation and compare the final spectra with the available experimental data. The $p_T$ spectra of $K^{*}(892)$ calculated directly by quark combination model are explicitly higher than the data at low $p_T \\lesssim 1.5$ GeV and taking into account the modification of rescattering effects the resulting final spectra well agree with the data at all three collision energies. The rescattering effect on $\\phi(1020)$ production is weak and including it can slightly improve our description at low $p_T$ on the...

  2. Energy dependence of resonance production in relativistic heavy ion collisions

    Science.gov (United States)

    Shao, Feng-Lan; Song, Jun; Wang, Rui-Qin; Zhang, Mao-Sheng

    2017-01-01

    The production of the hadronic resonances K*0(892), ϕ(1020), Σ*(1385), and Ξ*(1530) in central AA collisions at , 200, and 2760 GeV is systematically studied. The direct production of these resonances at system hadronization is described by the quark combination model and the effects of hadron multiple-scattering stage are dealt with by a ultra-relativistic quantum molecular dynamics model (UrQMD). We study the contribution of these two production sources to final observation and compare the final spectra with the available experimental data. The p T spectra of K*0(892) calculated directly by quark combination model are explicitly higher than the data at low p T ≲ 1.5 GeV, and taking into account the modification of rescattering effects, the resulting final spectra well agree with the data at all three collision energies. The rescattering effect on ϕ(1020) production is weak and including it can slightly improve our description at low p T on the basis of overall agreement with the data. We also predict the p T spectra of Σ*(1385) and Ξ*(1530), to be tested by the future experimental data. Supported by National Natural Science Foundation of China (11575100, 11305076, 11505104)

  3. High energy particle collisions and geometry of horizon

    CERN Document Server

    Zaslavskii, O B

    2016-01-01

    We consider collision of two geodesic particles near the horizon of such an axially symmetric black hole (rotating or static) that the metric coefficient $g_{\\phi \\phi }\\rightarrow 0$ there. It is shown that (both for regular and singular horizons) the energy in the centre of mass frame $% E_{c.m.}$ is indefinitely large even without fine-tuning of particles' parameters. Kinematically, this is collision between two rapid particles that approach the horizon almost with the speed of light but at different angles. The latter is the reason why the relative velocity tends to that of light, hence to high $E_{c.m.}$. Our approach is model-independent. It relies on general properties of geometry and is insensitive to the details of material source that supports the geometies of the type under consideration. For several particular models (the stringy black hole, the Brans-Dicke analogue of the Schwarzschild metric and the Janis-Newman-Winicour one) we recover the results found in literature previously.

  4. Covariance Analysis of Symmetry Energy Observables from Heavy Ion Collision

    CERN Document Server

    Zhang, Yingxun; Li, Zhuxia

    2015-01-01

    Using covariance analysis, we quantify the correlations between the interaction parameters in a transport model and the observables commonly used to extract information of the Equation of State of Asymmetric Nuclear Matter in experiments. By simulating $^{124}$Sn+$^{124}$Sn, $^{124}$Sn+$^{112}$Sn and $^{112}$Sn+$^{112}$Sn reactions at beam energies of 50 and 120 MeV per nucleon, we have identified that the nucleon effective mass splitting are most strongly correlated to the neutrons and protons yield ratios with high kinetic energy from central collisions especially at high incident energy. The best observable to determine the slope of the symmetry energy, L, at saturation density is the isospin diffusion observable even though the correlation is not very strong ($\\sim$0.7). Similar magnitude of correlation but opposite in sign exists for isospin diffusion and nucleon isoscalar effective mass. At 120 MeV/u, the effective mass splitting and the isoscalar effective mass also have opposite correlation for the do...

  5. Percolation approach to initial stage effects in high energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Brijesh K.

    2014-06-15

    Possible phase transition of strongly interacting matter from hadron to a quark–gluon plasma state have in the past received considerable interest. The clustering of color sources provides a framework of the partonic interactions in the initial stage of the collisions. The onset of deconfinement transition is identified by the spanning percolation cluster in 2D percolation. In this talk results are presented both for the multiplicity and the elliptic flow at RHIC and LHC energies. The thermodynamic quantities temperature, equation of state and transport coefficient are obtained in the framework of clustering of color sources. It is shown that the results are in excellent agreement with the recent lattice QCD calculations (LQCD)

  6. Percolation Approach to Initial Stage Effects in High Energy Collisions

    CERN Document Server

    Srivastava, Brijesh K

    2014-01-01

    Possible phase transition of strongly interacting matter from hadron to a quark-gluon plasma state have in the past received considerable interest. The clustering of color sources provides a framework of the the partonic interactions in the initial stage of the collisions. The onset of de-confinement transition is identified by the spanning percolation cluster in 2D percolation. In this talk results are presented both for the multiplicity and the elliptic flow at RHIC and LHC energies. The thermodynamic quantities temperature, equation of state and transport coefficient are obtained in the framework of clustering of color sources. It is shown that the results are in excellent agreement with the recent lattice QCD calculations(LQCD).

  7. High-energy collisions of particles, strings, and branes

    CERN Document Server

    Veneziano, Gabriele

    2015-01-01

    This chapter summarizes some 25 years of work on the transplanckian-energy collisions of particles, strings, and branes, seen as a theoretical laboratory for understanding how gravity and quantum mechanics can be consistently combined in string theory. The ultimate aim of the exercise is to understand whether and how a consistent quantization of gravity can solve some longstanding paradoxes, such as the apparent loss of information in the production and decay of black holes at a semiclassical level. Considerable progress has been made in understanding the emergence of General Relativity expectations and in evaluating several kinds of quantum string corrections to them in the weak-gravity regime while keeping unitarity manifest. While some progress has also been made in the strong-gravity/gravitational collapse domain, full control of how unitarity works in that regime is still lacking.

  8. Solitary and freak waves in superthermal plasma with ion jet

    Science.gov (United States)

    Abdelsalam, U. M.; Abdelsalam

    2013-06-01

    The nonlinear solitary and freak waves in a plasma composed of positive and negative ions, superthermal electrons, ion beam, and stationary dust particles have been investigated. The reductive perturbation method is used to obtain the Korteweg-de Vries (KdV) equation describing the system. The latter admits solitary wave solution, while the dynamics of the modulationally unstable wavepackets described by the KdV equation gives rise to the formation of freak/rogue excitation described by the nonlinear Schrödinger equation. In order to show that the characteristics of solitary and freak waves are influenced by plasma parameters, relevant numerical analysis of appropriate nonlinear solutions are presented. The results from this work predict nonlinear excitations that may associate with ion jet and superthermal electrons in Herbig-Haro objects.

  9. Radiative torques on interstellar grains; 1, superthermal spinup

    CERN Document Server

    Draine, B T; Weingartner, Joseph C

    1996-01-01

    Irregular dust grains are subject to radiative torques when irradiated by interstellar starlight. It is shown how these radiative torques may be calculated using the discrete dipole approximation. Calculations are carried out for one irregular grain geometry, and three different grain sizes. It is shown that radiative torques can play an important dynamical role in spinup of interstellar dust grains, resulting in rotation rates which may exceed even those expected from H_2 formation on the grain surface. Because the radiative torque on an interstellar grain is determined by the overall grain geometry rather than merely the state of the grain surface, the resulting superthermal rotation is expected to be long-lived. By itself, long-lived superthermal rotation would permit grain alignment by normal paramagnetic dissipation on the "Davis-Greenstein" timescale. However, radiative torques arising from anisotropy of the starlight background can act directly to alter the grain alignment on much shorter timescales, a...

  10. Charged particle density distributions in Au + Au collisions at relativistic heavy-ion collider energies

    Indian Academy of Sciences (India)

    Fauad Rami

    2003-05-01

    Charged particle pseudorapidity distributions have been measured in Au + Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions of different parton scattering models and the important role of hard scattering processes at RHIC energies is discussed.

  11. Midrapidity inclusive densities in high energy pp collisions in additive quark model

    Science.gov (United States)

    Shabelski, Yu. M.; Shuvaev, A. G.

    2016-08-01

    High energy (CERN SPS and LHC) inelastic pp (pbar{p}) scattering is treated in the framework of the additive quark model together with Pomeron exchange theory. We extract the midrapidity inclusive density of the charged secondaries produced in a single quark-quark collision and investigate its energy dependence. Predictions for the π p collisions are presented.

  12. Collision Induced Dissociation and Energy Transfer in Molecular Hydroge

    Science.gov (United States)

    Mandy, Margot E.

    2006-06-01

    Molecular hydrogen is a significant constituent in giant molecular clouds in the interstellar medium. Shocks in these clouds are associated with star formation. The cooling of the shocks is governed by competition of collisional energy transfer and dissociation with radiative cooling by quadrupole emission. Thus a detailed understanding of collisional behaviour of molecular hydrogen is needed. Work in this group has examined energy transfer and dissociation in molecular energy transfer as the result of collisions with H, D, He, and H2. Using quasiclassical trajectories and chemically accurate ab initio potentials state-to-state rate coefficients have been determined. The uncertainties of the cross sections are propagated rigourously to give uncertainties of the rate coefficients and the rate coefficients are parameterized as a function of temperature. Comparisons with quantum calculations are discussed and the proposed website is described.This work was supported by a grant from the Natural Sciences and Engineering Research Council of Canada. The calculations were carried out using the high performance computing facility jointly supported by the Canadian Foundation for Innovation, the British Columbia Knowledge Development Fund, and Silicon Graphics at the University of Northern British Columbia.

  13. Modulational instability of a Langmuir wave in plasmas with energetic tails of superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, I. V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation)

    2013-01-15

    The impact of superthermal electrons on dispersion properties of isotropic plasmas and on the modulational instability of a monochromatic Langmuir wave is studied for the case when the power-law tail of the electron distribution function extends to relativistic velocities and contains most of the plasma kinetic energy. Such an energetic tail of electrons is shown to increase the thermal correction to the Langmuir wave frequency, which is equivalent to the increase of the effective electron temperature in the fluid approach, and has almost no impact on the dispersion of ion-acoustic waves, in which the role of temperature is played by the thermal spread of low-energy core electrons. It is also found that the spectrum of modulational instability in the non-maxwellian plasma narrows significantly, as compared to the equilibrium case, without change of the maximum growth rate and the corresponding wavenumber.

  14. Modulational instability of a Langmuir wave in plasmas with energetic tails of superthermal electrons

    CERN Document Server

    Timofeev, I V

    2012-01-01

    The impact of superthermal electrons on dispersion properties of isotropic plasmas and on the modulational instability of a monochromatic Langmuir wave is studied for the case when the power-law tail of the electron distribution function extends to relativistic velocities and contains most of the plasma kinetic energy. Such an energetic tail of electrons is shown to increase the thermal correction to the Langmuir wave frequency, which is equivalent to the increase of the effective electron temperature in the fluid approach, and has almost no impact on the dispersion of ion-acoustic waves, in which the role of temperature is played by the thermal spread of low-energy core electrons. It is also found that the spectrum of modulational instability in the non-maxwellian plasma narrows significantly, as compared to the equilibrium case, without change of the maximum growth rate and the corresponding wavenumber.

  15. Finite escape fraction for ultrahigh energy collisions around Kerr naked singularity

    Indian Academy of Sciences (India)

    Mandar Patil; Pankaj S Joshi

    2015-04-01

    We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location = M around the Kerr naked singularity if the Kerr spin parameter transcends unity by an infinitesimally small amount → 1+. The collision is between initially ingoing particle that turns back as an outgoing particle due to angular momentum barrier, with another ingoing particle. We assume that two massless particles are produced in such a collision and their angular distribution is isotropic in the centre-of-mass frame. We calculated the escape fraction for the massless particles to reach infinity. We showed that the escape fraction is finite and approximately equal to half for the ultrahigh energy collisions. Therefore, the particles produced in high-energy collisions would escape to infinity providing the signature of the nature of basic interactions at those energies. This result is in contrast with the case of extremal Kerr black hole where almost all particles produced in high-energy collisions are absorbed by the black hole rendering collisions unobservable.

  16. Search for Nuclei in Heavy Ion Collisions at Ultrarelativistic Energies

    CERN Multimedia

    2002-01-01

    We would like to know if nuclei are still present after a collision of two heavy ions at ultrarelativistic energies. If one can detect some of them at large angle ($>$10-15|0) they very likely come from a multifragmentation of the excited target spectators. Such a multifragmentation in several nuclei has been in proton induced reactions at Fermilab and it was interpreted as a gas-liquid phase transition in nuclei matter near the critical point. With heavy ions the energy deposited in the target spectators will be much higher than in the case of protons and a different mechanism should be involved if nuclei are still observed. \\\\ \\\\ We propose to detect nuclei using 1-2 silicon telescopes and a 1-2mg/cm|2 Au target bombarded by an |1|6O or |3|2S beam at 226 GeV/u. The set-up will be installed in a small cube located just before the NA38 experiment and should not perturb it.\\\\ \\\\ Data from |1|6O incident on Au have been taken last year. The experiment is presently taking data with |3|2S ions.

  17. Gluino pair production in high-energy photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Berge, S.; Klasen, M. [II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761, Hamburg (Germany)

    2003-09-01

    We study the potential of high-energy photon colliders for the production of gluino pairs within the minimal supersymmetric standard model (MSSM). In this model, the process {gamma}{gamma}{yields}gg is mediated by quark/squark box diagrams with enhancements for up-type quarks/squarks from their larger charges and for third generation squarks from their large mass splittings, generated by the mixing of left- and right-handed states. Far above threshold and in scenarios with very heavy squarks, resolved photons can contribute significantly at tree level. Taking into account the laser photon backscattering spectrum, electron and laser beam polarization effects, and current mass exclusion limits, we find that gluino pair production in high-energy photon collisions should be visible over large regions of the MSSM parameter space, contrary to what has been found for e{sup +}e{sup -} annihilation. In addition, the cross section rises rather steeply, so that a gluino mass determination with a precision of a few GeV should be feasible for a wide range of post-LEP benchmark points. (orig.)

  18. Gluino pair production in high-energy photon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Berge, S.; Klasen, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2003-03-01

    We study the potential of high-energy photon colliders for the production of gluino pairs within the minimal supersymmetric standard model (MSSM). In this model, the process {gamma}{gamma} {yields} gg is mediated by quark/squark box diagrams with enhancements for up-type quarks/squarks from their larger charges and for third generation squarks from their large mass splittings, generated by the mixing of left- and right-handed states. Far above threshold and in scenarios with very heavy squarks, resolved photons can contribute significantly at tree level. Taking into account the laser photon backscattering spectrum, electron and laser beam polarization effects, and current mass exclusion limits, we find that gluino pair production in high-energy photon collisions should be visible over large regions of the MSSM parameter space, contrary to what has been found for e{sup +}e{sup -} annihilation. In addition, the cross section rises rather steeply, so that a gluino mass determination with a precision of a few GeV should be feasible for a wide range of post-LEP benchmark points. (orig.)

  19. Energy- Angular Correlation of Medium Energy Particles Produced in Heavy Ion Collisions

    CERN Document Server

    Hussein, M T; Sadek, N M; Elsweedy, J; Elsweedy, Jamila

    2004-01-01

    The nuclear photo-emulsion technique is used to study the information carried by the medium energy nucleons produced in heavy ion collisions. Multiplicity, energies as well as the angular distribution of this type of particles are measured. Due to the difficulties in measuring the energy only some particles having special criteria could be selected to measure their energy with consenting accuracy. A hypothetical model is proposed to correlate the energy of the produced particles to their emission angles so that it becomes easy to estimate the energy distribution in terms of measured emission angle. The proposed model is constructed upon statistical thermodynamic assumptions. Moreover, two additional base functions are originated that play the role of the statistical angular weight factor and the nuclear density of the compressed nuclear matter at the moment of particle emission. The prediction of the model are compared with complete set of measured data of the reactions of proton, helium, carbon and neon nucl...

  20. Improved Multibody Dynamics for Investigating Energy Dissipation in Train Collisions Based on Scaling Laws

    Directory of Open Access Journals (Sweden)

    Heng Shao

    2016-01-01

    Full Text Available This study aimed to investigate energy dissipation in train collisions. A 1/8 scaled train model, about one-dimensional in longitudinal direction, was used to carry out a scaled train collision test. Corresponding multibody dynamic simulations were conducted using traditional and improved method model (IMM in ADAMS. In IMM, the connection between two adjacent cars was expressed by a nonlinear spring and energy absorbing structures were equivalently represented by separate forces, instead of one force. IMM was able to simulate the motion of each car and displayed the deformation of structures at both ends of the cars. IMM showed larger deformations and energy absorption of structures in moving cars than those in stationary cars. Moreover, the asymmetry in deformation proportion in main energy absorbing structures decreased with increasing collision speed. The asymmetry decreased from 11.69% to 3.60% when the collision speed increased from 10 km/h to 36 km/h.

  1. Time-scaled scenario of low-energy heavy-ion collisions

    CERN Document Server

    Iwata, Yoritaka

    2013-01-01

    The underlying scenario of low-energy heavy-ion collisions is presented based on time-dependent density-functional calculations. A classification of several types of reaction dynamics is given with respect to their time-scales.

  2. Collision Energy Evolution of Elliptic and Triangular Flow in a Hybrid Model

    CERN Document Server

    Auvinen, Jussi

    2013-01-01

    While the existence of a strongly interacting state of matter, known as 'quark-gluon plasma' (QGP), has been established in heavy ion collision experiments in the past decade, the task remains to map out the transition from the hadronic matter to the QGP. This is done by measuring the dependence of key observables (such as particle suppression and elliptic flow) on the collision energy of the heavy ions. This procedure, known as 'beam energy scan', has been most recently performed at the Relativistic Heavy Ion Collider (RHIC). Utilizing a Boltzmann+hydrodynamics hybrid model, we study the collision energy dependence of initial state eccentricities and the final state elliptic and triangular flow. This approach is well suited to investigate the relative importance of hydrodynamics and hadron transport at different collision energies.

  3. Collision energy alteration during mass spectrometric acquisition is essential to ensure unbiased metabolomic analysis

    CSIR Research Space (South Africa)

    Madala, NE

    2012-08-01

    Full Text Available extracted from elicited tobacco cells revealed different clustering and different distribution patterns. As expected, ion abundance decreases with increasing collision energy, but, more importantly, results in unique multivariate data patterns from the same...

  4. The complete T-->V,R energy conversion in three-body collisions within the hard sphere model.

    Science.gov (United States)

    Azriel, Vladimir M; Rusin, Lev Yu; Sevryuk, Mikhail B

    2005-02-15

    It is shown that in hard sphere (impulsive) collisions of atoms with diatomic molecules, complete conversion of the collision energy into the internal energy of the diatomic partner is possible for any number of impacts between the elastic balls representing the particles. The corresponding collision geometries and relations between the masses of the particles are described in detail.

  5. Jet energy loss in heavy ion collisions from RHIC to LHC energies

    CERN Document Server

    Levai, Peter

    2011-01-01

    The suppression of hadron production originated from the induced jet energy loss is one of the most accepted and well understood phenomena in heavy ion collisions, which indicates the formation of color deconfined matter consists of quarks, antiquarks and gluons. This phenomena has been seen at RHIC energies and now the first LHC results display a very similar effect. In fact, the suppression is so close to each other at 200 AGeV and 2.76 ATeV, that it is interesting to investigate if such a suppression pattern can exist at all. We use the Gyulassy-Levai-Vitev description of induced jet energy loss combined with different nuclear shadowing functions and describe the experimental data. We claim that a consistent picture can be obtained for the produced hot matter with a weak nuclear shadowing. The interplay between nuclear shadowing and jet energy loss playes a crucial role in the understanding of the experimental data.

  6. Anisotropy of low energy direct photons in relativistic heavy ion collisions

    Science.gov (United States)

    Koide, T.; Kodama, T.

    2016-09-01

    Using the Wigner function approach for electromagnetic radiation fields, we investigate the behavior of low energy photons radiated by the deceleration processes of two colliding nuclei in relativistic heavy ion collisions. The angular distribution reveals information of the initial geometric configurations, which is reflected in the anisotropic parameter v 2, with an increasing v 2 as energy decreases. This behavior is qualitatively different to the v 2 from the hadrons produced in the collisions.

  7. Anisotropicity of Low Energy Direct Photons in Relativistic Heavy Ion Collisions

    CERN Document Server

    Koide, T

    2016-01-01

    We investigate the behavior of low energy photons radiated by deceleration processes of two colliding nuclei in relativistic heavy ion collisions, where their angular distribution reveals information of the initial geometric configurations. Such a property is reflected in the anisotropic parameter v_{2}, showing an increasing v_{2} as energy decreases, which is qualitatively different behavior from v_{2} from hadrons produced in the collisions.

  8. High energy pA collisions in the color glass condensate approach II. Quark production

    CERN Document Server

    Blaizot, J P; Venugopalan, R

    2004-01-01

    We compute the production of quark-antiquark pairs in high energy collisions between a small and a large projectile, as in proton-nucleus collisions, in the framework of the Color Glass Condensate. We derive a general expression for quark pair-production, which is not k_t-factorizable. However, k_t-factorization is recovered in the limit of large mass pairs or large quark--anti-quark momenta. Our results are amenable to a simple interpretation and suggest how multi-parton correlations at small x can be quantified in high-energy proton/deuteron-nucleus collisions.

  9. Time evolution of pion emission in heavy ion collisions at SIS energies

    CERN Document Server

    Oeschler, H

    1999-01-01

    Using a magnetic spectrometer pions, kaons and protons were detected in mass-symmetric heavy ion reactions from C+C to Au+Au and at incident energies between 0.6 and 2.0 A centre dot GeV. The center-of-mass pion spectra deviate from a Boltzmann distribution for all collision systems. Results are presented indicating that high-energy pions are emitted at an early stage of the collision. This is based on (i) a comparison of pi sup + and pi sup - spectra and (ii) the shielding of pions by spectator matter in peripheral collisions.

  10. Beam Energy Scan a Case for the Chiral Magnetic Effect in Au-Au Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Longacre, R. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2014-01-05

    The Chiral Magnetic Effect (CME) is predicted for Au-Au collisions at RHIC. However, many backgrounds can give signals that make the measurement hard to interpret. The STAR experiment has made measurements at different collisions energy ranging from √(sNN)=7.7 GeV to 62.4 GeV. In the analysis that is presented we show that the CME turns on with energy and is not present in central collisions where the induced magnetic is small.

  11. Studies of QCD structure in high-energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nadolsky, Pavel M. [Southern Methodist Univ., Dallas, TX (United States)

    2016-06-26

    ”Studies of QCD structure in high-energy collisions” is a research project in theoretical particle physics at Southern Methodist University funded by US DOE Award DE-SC0013681. The award furnished bridge funding for one year (2015/04/15-2016/03/31) between the periods funded by Nadolsky’s DOE Early Career Research Award DE-SC0003870 (in 2010-2015) and a DOE grant DE-SC0010129 for SMU Department of Physics (starting in April 2016). The primary objective of the research is to provide theoretical predictions for Run-2 of the CERN Large Hadron Collider (LHC). The LHC physics program relies on state-of-the-art predictions in the field of quantum chromodynamics. The main effort of our group went into the global analysis of parton distribution functions (PDFs) employed by the bulk of LHC computations. Parton distributions describe internal structure of protons during ultrarelivistic collisions. A new generation of CTEQ parton distribution functions (PDFs), CT14, was released in summer 2015 and quickly adopted by the HEP community. The new CT14 parametrizations of PDFs were obtained using benchmarked NNLO calculations and latest data from LHC and Tevatron experiments. The group developed advanced methods for the PDF analysis and estimation of uncertainties in LHC predictions associated with the PDFs. We invented and refined a new ’meta-parametrization’ technique that streamlines usage of PDFs in Higgs boson production and other numerous LHC processes, by combining PDFs from various groups using multivariate stochastic sampling. In 2015, the PDF4LHC working group recommended to LHC experimental collaborations to use ’meta-parametrizations’ as a standard technique for computing PDF uncertainties. Finally, to include new QCD processes into the global fits, our group worked on several (N)NNLO calculations.

  12. Transverse-momentum and collision-energy dependence of high-pT hadron suppression in Au+Au collisions at ultrarelativistic energies.

    Science.gov (United States)

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Drees, K A; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-10-24

    We report high statistics measurements of inclusive charged hadron production in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. A large, approximately constant hadron suppression is observed in central Au+Au collisions for 5collision energy dependence of the yields and the centrality and p(T) dependence of the suppression provide stringent constraints on theoretical models of suppression. Models incorporating initial-state gluon saturation or partonic energy loss in dense matter are largely consistent with observations. We observe no evidence of p(T)-dependent suppression, which may be expected from models incorporating jet attenuation in cold nuclear matter or scattering of fragmentation hadrons.

  13. Ultra-high energy particle collisions in a regular spacetime without blackholes or naked singularities

    CERN Document Server

    Patil, Mandar

    2012-01-01

    We investigate here the particle acceleration and collisions with extremely large center of mass energies in a perfectly regular spacetime containing neither singularity nor an event horizon. The ultra-high energy collisions of particles near the event horizon of extremal Kerr blackhole, and also in many other examples of extremal blackholes have been investigated and reported recently. We studied an analogous particle acceleration process in the Kerr and Reissner- Nordstrom spacetimes without horizon, containing naked singularities. Further to this, we show here that the particle acceleration and collision process is in fact independent of blackholes and naked singularities, and can happen in a fully regular spacetime containing neither of these. We derive the conditions on the general static spherically symmetric metric for such a phenomena to happen. We show that in order to have ultra-high energy collisions it is necessary for the norm of the timelike Killing vector to admit a maximum with a vanishingly s...

  14. A Schamel equation for ion acoustic waves in superthermal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Williams, G., E-mail: gwilliams06@qub.ac.uk; Kourakis, I. [Centre for Plasma Physics, Department of Physics and Astronomy, Queen' s University Belfast, BT7 1NN, Northern Ireland (United Kingdom); Verheest, F. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B-9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Hellberg, M. A. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Anowar, M. G. M. [Department of Physics, Begum Rokeya University, Rangpur, Rangpur-5400 (Bangladesh)

    2014-09-15

    An investigation of the propagation of ion acoustic waves in nonthermal plasmas in the presence of trapped electrons has been undertaken. This has been motivated by space and laboratory plasma observations of plasmas containing energetic particles, resulting in long-tailed distributions, in combination with trapped particles, whereby some of the plasma particles are confined to a finite region of phase space. An unmagnetized collisionless electron-ion plasma is considered, featuring a non-Maxwellian-trapped electron distribution, which is modelled by a kappa distribution function combined with a Schamel distribution. The effect of particle trapping has been considered, resulting in an expression for the electron density. Reductive perturbation theory has been used to construct a KdV-like Schamel equation, and examine its behaviour. The relevant configurational parameters in our study include the superthermality index κ and the characteristic trapping parameter β. A pulse-shaped family of solutions is proposed, also depending on the weak soliton speed increment u{sub 0}. The main modification due to an increase in particle trapping is an increase in the amplitude of solitary waves, yet leaving their spatial width practically unaffected. With enhanced superthermality, there is a decrease in both amplitude and width of solitary waves, for any given values of the trapping parameter and of the incremental soliton speed. Only positive polarity excitations were observed in our parametric investigation.

  15. Collective flows in high-energy heavy-ion collisions at AGS and SPS energies

    Indian Academy of Sciences (India)

    A Ohnishi; M Isse; N Otuka; P K Sahu; Y Nara

    2006-04-01

    Proton collective flows in heavy-ion collisions from AGS ((2–11) A GeV) to SPS ((40, 158) A GeV) energies are investigated in a nonequilibrium transport model with nuclear mean-field (MF). Sideward , directed 1, and elliptic 2 flows are systematically studied with different assumptions on the nuclear equation of state (EoS). We find that momentum dependence in the nuclear MF is important for understanding the proton collective flows at AGS and SPS energies. Calculated results with momentum-dependent MF qualitatively reproduce the experimental data of proton sideward, directed, and elliptic flows in an incident energy range of (2–158) A GeV.

  16. Nonplanar ion-acoustic shocks in electron–positron–ion plasmas: Effect of superthermal electrons

    Indian Academy of Sciences (India)

    Deb Kumar Ghosh; Prasantha Chatterjee; Pankaj Kumar Mandal; Biswajit Sahu

    2013-09-01

    Ion-acoustic shock waves (IASWs) in a homogeneous unmagnetized plasma, comprising superthermal electrons, positrons, and singly charged adiabatically hot positive ions are investigated via two-dimensional nonplanar Kadomstev–Petviashvili–Burgers (KPB) equation. It is found that the profiles of the nonlinear shock structures depend on the superthermality of electrons. The influence of other plasma parameters such as, ion kinematic viscosity and ion temperature, is discussed in the presence of superthermal electrons in nonplanar geometry. It is also seen that the IASWs propagating in cylindrical/spherical geometry with transverse perturbation will be deformed as time goes on.

  17. Introduction to high-energy heavy-ion collisions

    CERN Document Server

    Wong, Cheuk-Yin

    1994-01-01

    Written primarily for researchers and graduate students who are new in this emerging field, this book develops the necessary tools so that readers can follow the latest advances in this subject. Readers are first guided to examine the basic informations on nucleon-nucleon collisions and the use of the nucleus as an arena to study the interaction of one nucleon with another. A good survey of the relation between nucleon-nucleon and nucleus-nucleus collisions provides the proper comparison to study phenomena involving the more exotic quark-gluon plasma. Properties of the quark-gluon plasma and s

  18. Collisions of low-energy antiprotons with molecular hydrogen: ionization, excitation and stopping power

    DEFF Research Database (Denmark)

    Lühr, Armin Christian; Saenz, Alejandro

    2009-01-01

    A time-dependent coupled-channel approach was used to calculate ionization, excitation, and energy-loss cross sections as well as energy spectra for antiproton and proton collisions with molecular hydrogen for impact energies 8 < E < 4000 keV....

  19. Free molecular collision cross section calculation methods for nanoparticles and complex ions with energy accommodation

    Energy Technology Data Exchange (ETDEWEB)

    Larriba, Carlos, E-mail: clarriba@umn.edu; Hogan, Christopher J.

    2013-10-15

    The structures of nanoparticles, macromolecules, and molecular clusters in gas phase environments are often studied via measurement of collision cross sections. To directly compare structure models to measurements, it is hence necessary to have computational techniques available to calculate the collision cross sections of structural models under conditions matching measurements. However, presently available collision cross section methods contain the underlying assumption that collision between gas molecules and structures are completely elastic (gas molecule translational energy conserving) and specular, while experimental evidence suggests that in the most commonly used background gases for measurements, air and molecular nitrogen, gas molecule reemission is largely inelastic (with exchange of energy between vibrational, rotational, and translational modes) and should be treated as diffuse in computations with fixed structural models. In this work, we describe computational techniques to predict the free molecular collision cross sections for fixed structural models of gas phase entities where inelastic and non-specular gas molecule reemission rules can be invoked, and the long range ion-induced dipole (polarization) potential between gas molecules and a charged entity can be considered. Specifically, two calculation procedures are described detail: a diffuse hard sphere scattering (DHSS) method, in which structures are modeled as hard spheres and collision cross sections are calculated for rectilinear trajectories of gas molecules, and a diffuse trajectory method (DTM), in which the assumption of rectilinear trajectories is relaxed and the ion-induced dipole potential is considered. Collision cross section calculations using the DHSS and DTM methods are performed on spheres, models of quasifractal aggregates of varying fractal dimension, and fullerene like structures. Techniques to accelerate DTM calculations by assessing the contribution of grazing gas

  20. Transverse energy production in {sup 208}Pb+Pb collisions at 158 GeV per nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Alber, T.; Appelshaeuser, H.; Baechler, J.; Bartke, J.; Bialkowska, H.; Bieser, F.; Bloomer, M.A.; Blyth, C.O.; Bock, R.; Bormann, C.; Brady, F.P.; Brockmann, R.; Buncic, P.; Caines, H.L.; Cebra, D.; Chan, P.; Cooper, G.E.; Cramer, J.G.; Cramer, P.B.; Csato, P.; Derado, I.; Dunn, J.; Eckardt, V.; Eckhardt, F.; Euler, S.; Ferguson, M.I.; Fischer, H.G.; Fodor, Z.; Foka, P.; Freund, P.; Fuchs, M.; Gal, J.; Gazdzicki, M.; Gladysz, E.; Grebieszkow, J.; Guenther, J.; Harris, J.W.; Heck, W.; Hegyi, S.; Hill, L.A.; Huang, I.; Howe, M.A.; Igo, G.; Irmscher, D.; Jacobs, P.; Jones, P.G.; Kadija, K.; Kecskemeti, J.; Kowalski, M.; Kuehmichel, A.; Lasiuk, B.; Margetis, S.; Mitchell, J.W.; Mock, A.; Nelson, J.M.; Odyniec, G.; Palinkas, J.; Palla, G.; Panagiotou, A.D.; Petridis, A.; Piper, A.; Poskanzer, A.M.; Prindle, D.J.; Puehlhofer, F.; Rauch, W.; Renfordt, R.; Retyk, W.; Ritter, H.G.; Roehrich, D.; Rudolph, H.; Runge, K.; Sandoval, A.; Sann, H.; Schaefer, E.; Schmitz, N.; Schoenfelder, S.; Seyboth, P.; Seyerlein, J.; Sikler, F.; Skrzypczak, E.; Stock, R.; Stroebele, H.; Szentpetery, I.; Sziklai, J.; Toy, M.; Trainor, T.A.; Trentalange, S.; Vassiliou, M.; Vesztergombi, G.; Vranic, D.; Wenig, S.; Whitten, C.; Wienold, T.; Wood, L.; Zimanyi, J.; Zhu, X.; Zybert, R. [Department of Physics, University of Athens, Athens (Greece)]|[Lawrence Berkeley Laboratory, University of California, Berkeley California (United States)]|[Birmingham University, Birmingham (United Kingdom)]|[Institute of Physics, Budapest (Hungary)]|[CERN, Geneva (Switzerland)]|[Institute of Nuclear Physics, Cracow (Poland)]|[Gesellschaft fuer Schwerionenforschung (GSI), Darmstadt (Germany)]|[University of California at Davis, Davis California (United States)]|[Fachbereich Physik der Universitaet, Frankfurt (Germany)]|[Fachbereich Physik der Universitaet, Freiburg (Germany)]|[University of California at Los Angeles, Los Angeles California (United States)

    1995-11-20

    Measurements of the forward and the transverse energy in 158 GeV per nucleon {sup 208}Pb+Pb collisions are presented. A total transverse energy of about 1 TeV is created in central collisions. An energy density of about 3GeV/fm{sup 3} is estimated for near head-on collisions. Only statistical fluctuations are seen in the ratio of electromagnetic to hadronic transverse energy. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  1. A model for energy transfer in collisions of atoms with highly excited molecules.

    Science.gov (United States)

    Houston, Paul L; Conte, Riccardo; Bowman, Joel M

    2015-05-21

    A model for energy transfer in the collision between an atom and a highly excited target molecule has been developed on the basis of classical mechanics and turning point analysis. The predictions of the model have been tested against the results of trajectory calculations for collisions of five different target molecules with argon or helium under a variety of temperatures, collision energies, and initial rotational levels. The model predicts selected moments of the joint probability distribution, P(Jf,ΔE) with an R(2) ≈ 0.90. The calculation is efficient, in most cases taking less than one CPU-hour. The model provides several insights into the energy transfer process. The joint probability distribution is strongly dependent on rotational energy transfer and conservation laws and less dependent on vibrational energy transfer. There are two mechanisms for rotational excitation, one due to motion normal to the intermolecular potential and one due to motion tangential to it and perpendicular to the line of centers. Energy transfer is found to depend strongly on the intermolecular potential and only weakly on the intramolecular potential. Highly efficient collisions are a natural consequence of the energy transfer and arise due to collisions at "sweet spots" in the space of impact parameter and molecular orientation.

  2. Exclusive glueball production in high energy nucleus-nucleus collisions

    CERN Document Server

    Machado, M V T

    2010-01-01

    The cross sections for the glueball candidates production in quasi-real photon-photon collisions and on central diffraction processes, i.e. double Pomeron exchange, in heavy ion interactions at RHIC and LHC are computed. The rates for these distinct production channels are compared and they may be a fruitful approach to the investigation of glueballs.

  3. Characteristics of particle production in high energy nuclear collisions a model-based analysis

    CERN Document Server

    Guptaroy, P; Bhattacharya, S; Bhattacharya, D P

    2002-01-01

    The present work pertains to the production of some very important negatively charged secondaries in lead-lead and gold-gold collisions at AGS, SPS and RHIC energies. We would like to examine here the role of the particular version of sequential chain model (SCM), which was applied widely in the past in analysing data on various high-energy hadronic collisions, in explaining now the latest findings on the features of particle production in the relativistic nucleus-nucleus collisions. The agreement between the model of our choice and the measured data is found to be modestly satisfactory in cases of the most prominent and abundantly produced varieties of the secondaries in the above-stated two nuclear collisions. (25 refs).

  4. Production mechanism of hot nuclei in violent collisions in the Fermi energy domain

    OpenAIRE

    Veselsky, M.

    2001-01-01

    A production mechanism of highly excited nuclei formed in violent collisions in the Fermi energy domain is investigated. The collision of two nuclei is decomposed into several stages which are treated separately. Simplified exciton concept is used for the description of pre-equilibrium emission. A modified spectator-participant scenario is used where motion along classical Coulomb trajectories is assumed. The participant and one of the spectator zones undergo incomplete fusion. Excitation ene...

  5. Isospin effects in central heavy-ion collisions at Fermi energy

    Directory of Open Access Journals (Sweden)

    Rivet M.-F.

    2012-07-01

    Full Text Available N/Z effects were observed on variables measured in central Xe on Sn collisions around the Fermi energy. Comparisons were made with dynamical simulations of collisions in which the symmetry term of the EOS was varied. In this framework it appeared that the observed effects were due to the dynamics of the reaction and not to the deexcitation of the hot primary fragments.

  6. Low energy heavy particle collisions relevant to gas divertor physics

    Energy Technology Data Exchange (ETDEWEB)

    Onda, Kunizo [Science Univ. of Tokyo (Japan)

    1997-01-01

    Cross sections for rotational and vibrational excitations of H{sub 2} molecules caused by impact of electron, proton, H atom, H{sub 2}, H{sub 2}{sup +}, or H{sup -} are compared with one another and reviewed for rotational excitations by examining an interaction potential between collision partners. It is pointed out what are difficulties in theoretical approaches to collision of atoms with H{sub 2} molecules initially in vibrationally and rotationally excited states. A theoretical approach developed by our group, which aims quantum mechanically to investigate vibrationally inelastic scattering, exchange reaction, or dissociation of molecule in vibrationally excited states collided with an atom or its ion, is presented. Newly obtained dissociation cross sections of H{sub 2} in vibrationally excited states by He impact are presented and compared in magnitude with those of H{sub 2} caused by electron impact. (author)

  7. Kelvin-Helmholz instability in high energy heavy ion collisions

    CERN Document Server

    Csernai, L P; Anderlik, Cs

    2011-01-01

    The dynamical development of collective flow is studied in a 3+1D fluid dynamical model, with globally symmetric, peripheral initial conditions, which take into account the shear flow caused by the forward motion on the projectile side and the backward motion on the target side. While at \\sqrt{s_{NN}} = 2.76 A TeV semi-peripheral Pb+Pb collisions the earlier predicted rotation effect is visible, at more peripheral collisions, with high resolution and low numerical viscosity the initial development of a Kelvin-Helmholz instability is observed, which alters the flow pattern considerably. This effect provides a precision tool for studying the low viscosity of Quark-gluon Plasma.

  8. Charmonium production in polarized high-energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M.; Kniehl, B.A.; Mihaila, L.N.; Steinhauser, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2003-06-01

    We investigate the inclusive production of prompt J/{psi} mesons in polarized hadron-hadron, photon-hadron, and photon-photon collisions in the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) providing all contributing partonic cross sections in analytic form. In the case of photoproduction, we also include the resolved-photon contributions. We present numerical results appropriate for BNL RHIC-Spin, the approved SLAC fixed-target experiment E161, and the e{sup +}e{sup -} and {gamma}{gamma} modes of TESLA. Specifically, we assess the feasibility to access the spin-dependent parton distributions in the polarized proton and photon. We also point out that preliminary data on J/{psi} inclusive production taken by the PHENIX Collaboration in unpolarized proton-proton collisions at RHIC tends to favor the NRQCD factorization hypothesis, while it significantly overshoots the theoretical prediction of the color-singlet model at large values of transverse momentum. (orig.)

  9. Antideuteron production in high energy heavy ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nagle, J.L.; Kumar, B.S.; Bennett, M.J.; Coe, S.D.; Diebold, G.E.; Pope, J.K. (A.W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06520-8124 (United States)); Jahns, A.; Sorge, H. (Institut fuer Theoretische Physik, 60054 Frankfurt am Main 11, (Germany))

    1994-10-31

    Experiment E858 at the Brookhaven National Laboratory Alternating Gradient Synchrotron has recently reported the detection of two antideuterons produced in 14.6[ital A] GeV/[ital c] Si+Au collisions. The data were interpreted as implying antideuteron production rates about an order of magnitude below expectations. We use an extended RQMD model to demonstrate that the antideuteron yields are readily explained in a dynamical scenario that includes collective expansion and strong antinucleon absorption.

  10. Evaluation of excitation energy and spin from light charged particles multiplicities in heavy-ion collisions

    CERN Document Server

    Steckmeyer, J C; Grotowski, K; Pawowski, P; Aiello, S; Anzalone, A; Bini, M; Borderie, B; Bougault, R; Cardella, G; Casini, G; Cavallaro, S; Charvet, J L; Dayras, R; De Filippo, E; Durand, D; Femin, S; Frankland, J D; Galíchet, E; Geraci, M; Giustolisi, F; Guazzoni, P; Iacono-Manno, M; Lanzalone, G; Lanzan, G; Le Neindre, N; Lo Nigro, S; Lo Piano, F; Olmi, A; Pagano, A; Papa, M; Pârlog, M; Pasquali, G; Piantelli, S; Pirrone, S; Politi, G; Porto, F; Rivet, M F; Rizzo, F; Rosato, E; Roy, R; Sambataro, S; Sperduto, M L; Stefanini, A A; Sutera, C; Tamain, B; Vient, E; Volant, C; Wieleczko, J P; Zetta, L

    2005-01-01

    A simple procedure for evaluating the excitation energy and the spin transfer in heavy-ion dissipative collisions is proposed. It is based on a prediction of the GEMINI evaporation code : for a nucleus with a given excitation energy, the average number of emitted protons decreases with increasing spin, whereas the average number of alpha particles increases. Using that procedure for the reaction 107Ag+58Ni at 52 MeV/nucleon, the excitation energy and spin of quasi-projectiles have been evaluated. The results obtained in this way have been compared with the predictions of a model describing the primary dynamic stage of heavy-ion collisions.

  11. Dynamical Analysis of Sputtering at Threshold Energy Range: Modelling of Ar+Ni(100) Collision System

    Institute of Scientific and Technical Information of China (English)

    HUNDUR Yakup; G(U)VEN(C) Ziya B; HIPPLER Rainer

    2008-01-01

    The sputtering process of Ar+Ni(100) collision systems is investigated by means of constant energy molecular dynamics simulations.The Ni(100) slab is mimicked by an embedded-atom potential,and the interaction between the projectile and the surface is modelled by using the reparametrized ZBL potential.Ni atom emission from the lattice is analysed over the range of 20-50 eV collision energy.Sputtering yield,angular and energy distributions of the scattered Ar and of the sputtered Ni atoms are calculated,and compared to the available theoretical and experimental data.

  12. Rapidity Profile of the Initial Energy Density in Heavy-Ion Collisions

    CERN Document Server

    Ozonder, Sener

    2013-01-01

    The rapidity dependence of the initial energy density in heavy-ion collisions is calculated from a three-dimensional McLerran-Venugopalan model (3dMVn) introduced by Lam and Mahlon. This model is infrared safe since global color neutrality is enforced. In this non-boost-invariant framework, the nuclei have non-zero thickness in the longitudinal direction. This results in Bjorken-x dependent unintegrated gluon distribution functions which lead to a rapidity-dependent initial energy density after the collision. The initial energy density and its rapidity dependence are important initial conditions for the quark gluon plasma and its hydrodynamic evolution.

  13. Inclusive and Exclusive observables from dipoles in high energy collisions

    CERN Document Server

    Flensburg, Christoffer; Lönnblad, Leif

    2011-01-01

    We present a new model for simulating exclusive final states in minimum-bias collisions between hadrons. In a series of papers we have developed a Monte Carlo model based on Mueller's dipole picture of BFKL-evolution, supplemented with non-leading corrections, which has shown to be very successful in describing inclusive and semi-inclusive observables in hadron collisions. In this paper we present a further extension of this model to also describe exclusive final states. This is a highly non-trivial extension, and we have encountered many details that influence the description, and for which no guidance from perturbative QCD could be found. Hence we have had to make many choices based on semi-classical and phenomenological arguments. The end result is a new event generator called DIPSY which can be used to simulate complete minimum-bias non-diffractive hadronic collision events. Although the description of data from the Tevatron and LHC is not quite as good as for PYTHIA, the most advanced of the general purp...

  14. Study of heavy ions collision at SIS energies with the detector FOPI; Etude des collisions d'ions lourds aux energies de SIS avec le detecteur FOPI

    Energy Technology Data Exchange (ETDEWEB)

    Bastid, N

    1999-09-23

    The present work has been carried out in the framework of experiments performed with the FOPI detector at the SIS/ESR accelerator facility of GSI-Darmstadt. It is devoted to the study of central and semi-central heavy ion collisions at beam energies ranging from 100 MeV to 2 GeV per nucleon. We present first generalities on relativistic heavy ion collisions then the FOPI detector with a special attention to the FOPI Inner Wall constructed by the Clermont-Ferrand group. The main results of the FOPI collaboration obtained with light and intermediate mass fragments and kaons are presented. A systematic study of the different forms of collection motion of nuclear matter, radial flow in very central reactions, sideward flow and squeeze-out in semi-central collisions, is performed. Further exciting possibilities concerning production and propagation of strangeness at SIS energies will be offered soon with the upgrade of the FOPI detector. The FOPI data have introduced constraints on parameters of theoretical models. Important progress concerning the knowledge of the properties of nuclear matter, the dynamics of the collisions and in-medium effects have been achieved. (author)

  15. Azimuthally-integrated HBT parameters for charged pions in nuclear-nuclear collisions versus initial energy

    CERN Document Server

    Okorokov, V A

    2014-01-01

    In the paper energy dependence of space-time extent of charged pion source is studied for various ion collisions for all experimentally available energies. There are no sharp changing of femtoscopy parameter values with increasing of $\\sqrt{s_{NN}}$ in domain of collision energies $\\sqrt{s_{NN}} \\geq 5$ GeV. Energy dependence of estimations for emission duration is almost flat for all energy domain under study within large error bars. Analytic function is suggested for smooth approximation of energy dependence of main HBT parameters. Fit curves demonstrate reasonable agreement with experimental data for most femtoscopy parameters in energy domain $\\sqrt{s_{NN}} \\geq 5$ GeV. Estimations of femtoscopy observables are obtained for energies of the LHC and FCC project.

  16. Fast computation of high energy elastic collision scattering angle for electric propulsion plume simulation

    Science.gov (United States)

    Araki, Samuel J.

    2016-11-01

    In the plumes of Hall thrusters and ion thrusters, high energy ions experience elastic collisions with slow neutral atoms. These collisions involve a process of momentum exchange, altering the initial velocity vectors of the collision pair. In addition to the momentum exchange process, ions and atoms can exchange electrons, resulting in slow charge-exchange ions and fast atoms. In these simulations, it is particularly important to accurately perform computations of ion-atom elastic collisions in determining the plume current profile and assessing the integration of spacecraft components. The existing models are currently capable of accurate calculation but are not fast enough such that the calculation can be a bottleneck of plume simulations. This study investigates methods to accelerate an ion-atom elastic collision calculation that includes both momentum- and charge-exchange processes. The scattering angles are pre-computed through a classical approach with ab initio spin-orbit free potential and are stored in a two-dimensional array as functions of impact parameter and energy. When performing a collision calculation for an ion-atom pair, the scattering angle is computed by a table lookup and multiple linear interpolations, given the relative energy and randomly determined impact parameter. In order to further accelerate the calculations, the number of collision calculations is reduced by properly defining two cut-off cross-sections for the elastic scattering. In the MCC method, the target atom needs to be sampled; however, it is confirmed that initial target atom velocity does not play a significant role in typical electric propulsion plume simulations such that the sampling process is unnecessary. With these implementations, the computational run-time to perform a collision calculation is reduced significantly compared to previous methods, while retaining the accuracy of the high fidelity models.

  17. Hybrid (particle in cell-fluid) simulation of ion-acoustic soliton generation including super-thermal and trapped electrons

    Energy Technology Data Exchange (ETDEWEB)

    Nopoush, M.; Abbasi, H. [Faculty of Physics, Amirkabir University of Technology, P. O. Box 15875-4413, Tehran (Iran, Islamic Republic of)

    2011-08-15

    The present paper is devoted to the simulation of the nonlinear disintegration of a localized perturbation into an ion-acoustic soliton in a plasma. Recently, this problem was studied by a simple model [H. Abbasi et al., Plasma Phys. Controlled Fusion 50, 095007 (2008)]. The main assumptions were (i) in the electron velocity distribution function (DF), the ion-acoustic soliton velocity was neglected in comparison to the electron thermal velocity, (ii) on the ion-acoustic evolution time-scale, the electron velocity DF was assumed to be stationary, and (iii) the calculation was restricted to the small amplitude case. In order to generalize the model, one has to consider the evolution of the electron velocity DF for finite amplitudes. For this purpose, a one dimensional electrostatic hybrid code, particle in cell (PIC)-fluid, was designed. It simulates the electrons dynamics by the PIC method and the cold ions dynamics by the fluid equations. The plasma contains a population of super-thermal electrons and, therefore, a Lorentzian (kappa) velocity DF is used to model the high energy tail in the electron velocity DF. Electron trapping is included in the simulation in view of their nonlinear resonant interaction with the localized perturbation. A Gaussian initial perturbation is used to model the localized perturbation. The influence of both the trapped and the super-thermal electrons on this process is studied and compared with the previous model.

  18. Second European study conference on molecular low energy collisions (MOLEC II)

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    The conference contained 52 papers on molecular low energy collisions including nonadiabatic transitions and excited states, vibrational and rotational energy transfer, chemical reactions, dissociation and ionization, general methods, potential surfaces, electronic excitation and excited states, inelastic scattering and anisotropic potentials, chemical reactions, and Van der Waals molecules. (JFP)

  19. Jet analysis by neural networks in high energy hadron-hadron collisions

    CERN Document Server

    De Felice, P; Pasquariello, G; De Felice, P; Nardulli, G; Pasquariello, G

    1995-01-01

    We study the possibility to employ neural networks to simulate jet clustering procedures in high energy hadron-hadron collisions. We concentrate our analysis on the Fermilab Tevatron energy and on the k_\\bot algorithm. We consider both supervised multilayer feed-forward network trained by the backpropagation algorithm and unsupervised learning, where the neural network autonomously organizes the events in clusters.

  20. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    DEFF Research Database (Denmark)

    Hvelplund, P; Nielsen, SB; Sørensen, M

    2001-01-01

    We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge stat...

  1. Modeling collision energy transfer in APCI/CID mass spectra of PAHs using thermal-like post-collision internal energy distributions

    Science.gov (United States)

    Solano, Eduardo A.; Mohamed, Sabria; Mayer, Paul M.

    2016-10-01

    The internal energy transferred when projectile molecular ions of naphthalene collide with argon gas atoms was extracted from the APCI-CID (atmospheric-pressure chemical ionization collision-induced dissociation) mass spectra acquired as a function of collision energy. Ion abundances were calculated by microcanonical integration of the differential rate equations using the Rice-Ramsperger-Kassel-Marcus rate constants derived from a UB3LYP/6-311G+(3df,2p)//UB3LYP/6-31G(d) fragmentation mechanism and thermal-like vibrational energy distributions p M (" separators=" E , T char ) . The mean vibrational energy excess of the ions was characterized by the parameter Tchar ("characteristic temperature"), determined by fitting the theoretical ion abundances to the experimental breakdown graph (a plot of relative abundances of the ions as a function of kinetic energy) of activated naphthalene ions. According to these results, the APCI ion source produces species below Tchar = 1457 K, corresponding to 3.26 eV above the vibrational ground state. Subsequent collisions heat the ions up further, giving rise to a sigmoid curve of Tchar as a function of Ecom (center-of-mass-frame kinetic energy). The differential internal energy absorption per kinetic energy unit (dEvib/dEcom) changes with Ecom according to a symmetric bell-shaped function with a maximum at 6.38 ± 0.32 eV (corresponding to 6.51 ± 0.27 eV of vibrational energy excess), and a half-height full width of 6.30 ± 1.15 eV. This function imposes restrictions on the amount of energy that can be transferred by collisions, such that a maximum is reached as kinetic energy is increased. This behavior suggests that the collisional energy transfer exhibits a pronounced increase around some specific value of energy. Finally, the model is tested against the CID mass spectra of anthracene and pyrene ions and the corresponding results are discussed.

  2. Quarkonium production in high energy proton-proton and proton-nucleus collisions

    CERN Document Server

    Conesa del Valle, Z; Fleuret, F; Ferreiro, E G; Kartvelishvili, V; Kopeliovich, B Z; Lansberg, J P; Lourenço, C; Martinez, G; Papadimitriou, V; Satz, H; Scomparin, E; Ullrich, T; Teryaev, O; Vogt, R; Wang, J X

    2011-01-01

    We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarisation studies. Thereafter, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in a broader perspective, we emphasize the need for new observables to investigate quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.

  3. Quarkonium production in high energy proton-proton and proton-nucleus collisions

    Energy Technology Data Exchange (ETDEWEB)

    Conesa del Valle, Z. [Institut Pluridisciplinaire Hubert Curien (IPHC), Universite de Strasbourg, CNRS-IN2P3, Strasbourg (France); European Organization for Nuclear Research (CERN), Geneva (Switzerland); Corcella, G. [INFN, Laboratori Nazionali di Frascati, Via E.Fermi 40, I-00044, Frascati (Italy); Fleuret, F. [LLR, Ecole polytechnique, CNRS/IN2P3, Palaiseau (France); Ferreiro, E.G. [Departamento de Fisica de Particulas and IGFAE, Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Kartvelishvili, V. [Lancaster University, Lancaster LA1 4YB,United Kingdom (United Kingdom); Kopeliovich, B. [Departamento de Fisica Universidad Tecnica Federico Santa Maria, Instituto de Estudios Avanzados en Ciencias e Ingenieria and Centro, Cientifico-Tecnologico de Valparaiso, Casilla 110-V, Valparaiso (Chile); Lansberg, J.P. [IPNO, Universite Paris-Sud 11, CNRS/IN2P3, F-91406 Orsay (France); Lourenco, C. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Martinez, G. [SUBATECH, Ecole des Mines de Nantes, Universite de Nantes, CNRS-IN2P3, Nantes (France); Papadimitriou, V. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, Illinois, 60510, U.S.A (United States); Satz, H. [Fakultaet fuer Physik, Universitaet Bielefeld (Germany); Scomparin, E. [INFN Torino, Via P. Giuria 1, Torino, I-10125 (Italy); Ullrich, T. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Teryaev, O. [Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna 141980 (Russian Federation); Vogt, R. [Physics Divsion, Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Physics Department, University of California at Davis, Davis, CA 95616 (United States); Wang, J.X. [Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918(4), Beijing, 100049 (China)

    2011-05-15

    We present a brief overview of the most relevant current issues related to quarkonium production in high energy proton-proton and proton-nucleus collisions along with some perspectives. After reviewing recent experimental and theoretical results on quarkonium production in pp and pA collisions, we discuss the emerging field of polarisation studies. Afterwards, we report on issues related to heavy-quark production, both in pp and pA collisions, complemented by AA collisions. To put the work in broader perpectives, we emphasize the need for new observables to investigate the quarkonium production mechanisms and reiterate the qualities that make quarkonia a unique tool for many investigations in particle and nuclear physics.

  4. Hawking-Unruh Hadronization and Strangeness Production in High Energy Collisions

    CERN Document Server

    Castorina, P

    2014-01-01

    The thermal multihadron production observed in different high energy collisions poses many basic problems: why do even elementary, $e^+e^-$ and hadron-hadron, collisions show thermal behaviour? Why is there in such interactions a suppression of strange particle production? Why does the strangeness suppression almost disappear in relativistic heavy ion collisions? Why in these collisions is the thermalization time less than $\\simeq 0.5$ fm/c? We show that the recently proposed mechanism of thermal hadron production through Hawking-Unruh radiation can naturally answer the previous questions. Indeed, the interpretation of quark- antiquark pairs production, by the sequential string breaking, as tunneling through the event horizon of colour confinement leads to thermal behavior with a universal temperature, $T \\simeq 170$ Mev,related to the quark acceleration, a, by $T=a/2\\pi$. The resulting temperature depends on the quark mass and then on the content of the produced hadrons, causing a deviation from full equilib...

  5. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au +Au Collisions at RHIC

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-03-01

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au +Au collisions for energies ranging from √{sN N }=7.7 to 200 GeV. The third harmonic v32{2 }=⟨cos 3 (ϕ1-ϕ2)⟩ , where ϕ1-ϕ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δ η =η1-η2 . Nonzero v32{2 } is directly related to the previously observed large-Δ η narrow-Δ ϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v32{2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v32{2 } is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v32{2 } for central collisions shows a minimum near √{sN N }=20 GeV .

  6. On the balance energy and nuclear dynamics in peripheral heavy-ion collisions

    CERN Document Server

    Chugh, Rajiv

    2010-01-01

    We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of $Ne^{20}+Ne^{20}$, $Ca^{40}+Ca^{40}$, $Ni^{58}+Ni^{58}$, $Nb^{93}+Nb^{93}$, $Xe^{131}+Xe^{131}$ and $Au^{197}+Au^{197}$ are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon-nucleon cross-sections between 40 - 55 mb explains the data nicely. Interestingly, balance energy follows a power law $\\propto{A^{\\tau}}$ for the mass dependence at all colliding geometries. The power factor $\\tau$ is close to -1/3 in central collisions whereas it is -2/3 for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.

  7. Production mechanism of hot nuclei in violent collisions in the Fermi energy domain

    CERN Document Server

    Veselsky, M

    2002-01-01

    A production mechanism of highly excited nuclei formed in violent collisions in the Fermi energy domain is investigated. Collision of two nuclei is decomposed into several stages which are treated separately. A simple phenomenological approach based on the exciton concept is used for the description of pre-equilibrium emission. For violent collisions, a modified spectator-participant scenario is used where relative motion along the classical Coulomb trajectories is assumed. A simple approach is used for description of the incomplete fusion of the participant and one of the spectator zones. Excitation energies of both fragments are determined. Results of the calculation are compared to wide range of recent experimental nuclear reaction data in the Fermi energy domain. Geometric aspects of pre-equilibrium emission are revealed. Properties of hot projectile-like, mid-velocity and fusion-like sources are discussed. An adequate overall agreement between experiment and calculation is obtained.

  8. Electron-positron pair creation in low-energy collisions of heavy bare nuclei

    CERN Document Server

    Maltsev, I A; Tupitsyn, I I; Bondarev, A I; Kozhedub, Y S; Plunien, G; Stoehlker, Th

    2014-01-01

    A new method for calculations of electron-positron pair-creation probabilities in low-energy heavy-ion collisions is developed. The approach is based on the propagation of all one-electron states via the numerical solving of the time-dependent Dirac equation in the monopole approximation. The electron wave functions are represented as finite sums of basis functions constructed from B-splines using the dual-kinetic-balance technique. The calculations of the created particle numbers and the positron energy spectra are performed for the collisions of bare nuclei at the energies near the Coulomb barrier with the Rutherford trajectory and for different values of the nuclear charge and the impact parameter. To examine the role of the spontaneous pair creation the collisions with a modified velocity and with a time delay are also considered. The obtained results are compared with the previous calculations and the possibility of observation of the spontaneous pair creation is discussed.

  9. Formation of Polyatomic Molecules on a Dust-Grain Analogue Using Superthermal H and O Atoms: Relevance to Discovery of Circumstellar H2O by Herschel

    Science.gov (United States)

    Madzunkov, S. M.; Chutjian, A.; Darrach, M. R.; MacAskill, J. A.; Ehrenfreund, P.; Vidali, G.

    2011-05-01

    Carbon dioxide (CO2), formaldehyde (H2CO), methanol (CH3OH), ethanol (CH3CH2OH), and formic acid (HCOOH) have been formed in separate measurements involving collisions of superthermal beams of H(2S) atoms and O(3P) atoms with CO and CH4 molecules adsorbed on a gold surface at 4.8K. The collision products are detected using temperature-programmed desorption and mass spectrometry. Identification of the species is made through use of the Metropolis random-walk algorithm as constrained by the fractionation patterns. The relevance of this work to the recent discovery of H2O at the star IRC+10216 by PACS-SPIRE/Herschel will be discussed in terms of the grain-mediated reaction O(3P, 1-5 eV) + H2(grain) → H2O(grain), in which the O(3P) arises from stellar UV photodissociation.

  10. Production of dimeson atoms in high-energy collisions

    Science.gov (United States)

    Afanasyev, L.; Gevorkyan, S.; Voskresenskaya, O.

    2017-04-01

    The production of two-meson electromagnetic bound states and free meson pairs π^+π^- , K^+K^- , π^+K^{∓} in relativistic collisions has been considered. It is shown that using of exact Coulomb wave functions for dimeson atom (DMA) allows one to calculate the yield of discrete states with the desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1 S to 2 P state, which is essential for the pionium Lamb shift measurements, has been obtained.

  11. Production of dimeson atoms in high-energy collisions

    Energy Technology Data Exchange (ETDEWEB)

    Afanasyev, L.; Gevorkyan, S.; Voskresenskaya, O. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2017-04-15

    The production of two-meson electromagnetic bound states and free meson pairs π{sup +}π{sup -}, K{sup +}K{sup -}, π{sup +}K{sup -+} in relativistic collisions has been considered. It is shown that using of exact Coulomb wave functions for dimeson atom (DMA) allows one to calculate the yield of discrete states with the desired accuracy. The relative probabilities of production of DMA and meson pairs in the free state are estimated. The amplitude of DMA transition from 1S to 2P state, which is essential for the pionium Lamb shift measurements, has been obtained. (orig.)

  12. Initial energy density of quark-gluon plasma in relativistic heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Wong, C.Y.

    1984-01-01

    Recently, there has been considerable interest in the central rapidity region of highly relativistic heavy-ion collisions. Such an interest stems from the possibility of creating hadron matter of high energy density which may exceed the critical energy density for a phase transition between ordinary confined matter and the unconfined quark-gluon plasma. The experimental searches and identification of the quark-gluon plasma may provide a new insight into the question of quark confinement. The estimate of the initial energy density is quite uncertain. The initial energy density is nonetheless an important physical quantity. It is one of the factors which determines whether the produced matter can undergo phase transition or not. The energy density has been estimated previously by using the color neutralization model of Brodsky et al. However, the color neutralization model gives a central rapidity multiplicity in heavy-ion collision too low by a factor of two. For this reason, we wish to obtain a better estimate of the energy density (in the central rapidity region). As is well known, a simple Glauber-type multiple collision model can reproduce the total multiplicity and multiplicity plateau near the central rapidity region to within 30%. The simple multiple collision model has an approximate validity as a gross description of the reaction process. We shall adopt a semiempirical approach. Using the multiple collision model and the thickness function of Glauber, we obtain analytical functional form for all the quantities in question. A single parameter, r/sub rms/, is adjusted to fit the experimental central rapidity multiplicity data. The semi-empirical results provide a useful tool to extrapolate to the unknown central rapidity region of heavy-ion collisions.

  13. A study of vorticity formation in high energy nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Becattini, F. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); INFN, Sezione di Firenze, Sesto F.no (Firenze) (Italy); Inghirami, G. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); Johann Wolfgang Goethe University, Frankfurt Institute for Advanced Studies (FIAS), Frankfurt am Main (Germany); Rolando, V.; Pagliara, G. [Universita di Ferrara, Dipartimento di Fisica e Scienze della Terra, Ferrara (Italy); INFN, Sezione di Ferrara, Ferrara (Italy); Beraudo, A.; De Pace, A.; Nardi, M. [INFN, Sezione di Torino, Turin (Italy); Del Zanna, L. [Universita di Firenze, Dipartimento di Fisica e Astronomia, Sesto F.no (Firenze) (Italy); INFN, Sezione di Firenze, Sesto F.no (Firenze) (Italy); INAF, Osservatorio Astrofisico di Arcetri, Florence (Italy); Chandra, V. [Indian Institute of Technology Gandhinagar, Ahmedabad, Gujrat (India)

    2015-09-15

    We present a quantitative study of vorticity formation in peripheral ultrarelativistic heavy-ion collisions at √(s{sub NN}) = 200 GeV by using the ECHO-QGP numerical code, implementing relativistic dissipative hydrodynamics in the causal Israel-Stewart framework in 3 + 1 dimensions with an initial Bjorken flow profile. We consider different definitions of vorticity which are relevant in relativistic hydrodynamics. After demonstrating the excellent capabilities of our code, which proves to be able to reproduce Gubser flow up to 8 fm/c, we show that, with the initial conditions needed to reproduce the measured directed flow in peripheral collisions corresponding to an average impact parameter b = 11.6 fm and with the Bjorken flow profile for a viscous Quark Gluon Plasma with η/s = 0.1 fixed, a vorticity of the order of some 10{sup -2} c/fm can develop at freeze-out. The ensuing polarization of Λ baryons does not exceed 1.4 % at midrapidity. We show that the amount of developed directed flow is sensitive to both the initial angular momentum of the plasma and its viscosity. (orig.)

  14. Centrality Dependence of Flow in High-Energy Nucleus-Nucleus Collisions

    Institute of Scientific and Technical Information of China (English)

    杨红艳; 周代翠; 杨纯斌; 蔡勖

    2002-01-01

    Directed flow and elliptic flow of final state particles in high-energy nucleus-nucleus collisions in the EMU01 experiment have been studied. The dependences of directed flow and elliptic flow on incident energy and impact centrality of outgoing particles are presented. The results exhibit strong dependence of flow on centrality and energy. We also suggest a more reliable way to determine the event plane resolution here.

  15. Hawking-Unruh Hadronization and Strangeness Production in High Energy Collisions

    Directory of Open Access Journals (Sweden)

    Paolo Castorina

    2014-01-01

    Full Text Available The thermal multihadron production observed in different high energy collisions poses many basic problems: why do even elementary, e+e- and hadron-hadron, collisions show thermal behaviour? Why is there in such interactions a suppression of strange particle production? Why does the strangeness suppression almost disappear in relativistic heavy ion collisions? Why in these collisions is the thermalization time less than ≃0.5 fm/c? We show that the recently proposed mechanism of thermal hadron production through Hawking-Unruh radiation can naturally answer the previous questions. Indeed, the interpretation of quark (q-antiquark (q̅ pairs production, by the sequential string breaking, as tunneling through the event horizon of colour confinement leads to thermal behavior with a universal temperature, T≃170 Mev, related to the quark acceleration, a, by T=a/2π. The resulting temperature depends on the quark mass and then on the content of the produced hadrons, causing a deviation from full equilibrium and hence a suppression of strange particle production in elementary collisions. In nucleus-nucleus collisions, where the quark density is much bigger, one has to introduce an average temperature (acceleration which dilutes the quark mass effect and the strangeness suppression almost disappears.

  16. Chemical Dynamics Simulations of Intermolecular Energy Transfer: Azulene + N2 Collisions.

    Science.gov (United States)

    Kim, Hyunsik; Paul, Amit K; Pratihar, Subha; Hase, William L

    2016-07-14

    Chemical dynamics simulations were performed to investigate collisional energy transfer from highly vibrationally excited azulene (Az*) in a N2 bath. The intermolecular potential between Az and N2, used for the simulations, was determined from MP2/6-31+G* ab initio calculations. Az* is prepared with an 87.5 kcal/mol excitation energy by using quantum microcanonical sampling, including its 95.7 kcal/mol zero-point energy. The average energy of Az* versus time, obtained from the simulations, shows different rates of Az* deactivation depending on the N2 bath density. Using the N2 bath density and Lennard-Jones collision number, the average energy transfer per collision ⟨ΔEc⟩ was obtained for Az* as it is collisionally relaxed. By comparing ⟨ΔEc⟩ versus the bath density, the single collision limiting density was found for energy transfer. The resulting ⟨ΔEc⟩, for an 87.5 kcal/mol excitation energy, is 0.30 ± 0.01 and 0.32 ± 0.01 kcal/mol for harmonic and anharmonic Az potentials, respectively. For comparison, the experimental value is 0.57 ± 0.11 kcal/mol. During Az* relaxation there is no appreciable energy transfer to Az translation and rotation, and the energy transfer is to the N2 bath.

  17. Jet quenching and γ-jet correlation in high-energy heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xin-Nian [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan 430079 (China); Nuclear Science Division Mailstop 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94740 (United States); Zhu, Yan [Departamento de Física de Partículas and IGFAE, Universidade de Santiago de Compostela, E-15706 Santiago de Compostela, Galicia (Spain)

    2014-12-15

    Medium modification of γ-tagged jets in high-energy heavy-ion collisions is investigated within a linearized Boltzmann transport model which includes both elastic parton scattering and induced gluon emission. In Pb + Pb collisions at √(s)=2.76 TeV, a γ-tagged jet is seen to lose 15% of its energy at 0–10% central collisions. Simulations also point to a sizable azimuthal angle broadening of γ-tagged jets at the tail of a distribution which should be measurable when experimental errors are significantly reduced. An enhancement at large z{sub jet}=p{sub L}/E{sub jet} in jet fragmentation function at the Large Hadron Collider (LHC) can be attributed to the dominance of leading particles in the reconstructed jet. A γ-tagged jet fragmentation function is shown to be more sensitive to jet quenching, therefore a better probe of the jet transport parameter.

  18. Catalysis of Black Holes/Wormholes Formation in High Energy Collisions

    CERN Document Server

    Aref'eva, I Ya

    2009-01-01

    We discuss various mechanisms of catalysis of black holes/wormholes (BH/WH) formation in particles collisions. The current paradigm suggests that BH/WH formation in particles collisions will happen when center of mass energies of colliding particles is sufficiently above the Planck scale (the transplanckian region). To estimate the BH/WH production we use the classical geometrical cross section. We confirm the classical geometrical cross section of the BH production reconsidering the process of two transplanckian particles collision in the rest frame of one of incident particles. This consideration permits to use the standard Thorne's hoop conjecture for a matter compressed into a region to prove a variant of the conjecture dealing with a total amount of compressed energy in the case of colliding particles. We calculate geometrical cross sections for different processes and for different background, in particular, for (A)dS. We show that results are in agreement with closed trapped surface (CTS) estimations t...

  19. Jet Energy Scale and its Uncertainties using the Heavy Ion Jet Reconstruction Algorithm in pp Collisions

    CERN Document Server

    Puri, Akshat; The ATLAS collaboration

    2017-01-01

    ATLAS uses a jet reconstruction algorithm in heavy ion collisions that takes as input calorimeter towers of size $0.1 \\times \\pi/32$ in $\\Delta\\eta \\times \\Delta\\phi$ and iteratively determines the underlying event background. This algorithm, which is different from the standard jet reconstruction used in ATLAS, is also used in the proton-proton collisions used as reference data for the Pb+Pb and p+Pb. This poster provides details of the heavy ion jet reconstruction algorithm and its performance in pp collisions. The calibration procedure is described in detail and cross checks using photon- jet balance are shown. The uncertainties on the jet energy scale and the jet energy resolution are described.

  20. Three-fluid hydrodynamics based event simulation for collisions at NICA and FAIR energies

    CERN Document Server

    Batyuk, P; Bleicher, M; Ivanov, Yu B; Karpenko, Iu; Merts, S; Nahrgang, M; Petersen, H; Rogachevsky, O

    2016-01-01

    We present a new event generator based on the three-fluid hydrodynamics approach for the early stage of the collision, followed by a particlization at the hydrodynamic decoupling surface to join to a microscopic transport model, UrQMD, to account for hadronic final state interactions. We present first results for nuclear collisions of the FAIR/NICA energy scan program (Au+Au collisions, $\\sqrt{s_{NN}}=4-11$ GeV). We address the directed flow of protons and pions as well as the proton rapidity distribution for two model EoS, one with a first order phase transition the other with a crossover type softening at high densities. The new simulation program has the unique feature that it can describe a hadron-to-quark matter transition which proceeds in the baryon stopping regime that is not accessible to previous simulation programs designed for higher energies.

  1. Triple parton scatterings in high-energy proton-proton collisions arXiv

    CERN Document Server

    d'Enterria, David

    2017-01-01

    A generic expression to compute triple parton scattering cross sections in high-energy proton-proton (pp) collisions is presented as a function of the corresponding single parton cross sections and the transverse parton profile of the proton encoded in an effective parameter σeff,TPS. The value of σeff,TPS is closely related to the similar effective cross section that characterizes double parton scatterings, and amounts to σeff,TPS=12.5±4.5  mb. Estimates for triple charm (cc¯) and bottom (bb¯) production in pp collisions at LHC and FCC energies are presented based on next-to-next-to-leading-order perturbative calculations for single cc¯, bb¯ cross sections. At s≈100  TeV, about 15% of the pp collisions produce three cc¯ pairs from three different parton-parton scatterings.

  2. Charge fluctuations in Au+Au collisions at RHIC energy

    Institute of Scientific and Technical Information of China (English)

    CAI; Xu(蔡勖); ZHOU; Daimei(周代梅); SA; Benhao(萨本豪)

    2003-01-01

    A hadron and string cascade model, JPCIAE, together with the corresponding Monte Carlo eventgenerator, has been employed in this paper to investigate further the charge fluctuations in Au+Au collisions at√Snn= 130 GeV. The default JPCIAE calculations are in good agreement with PHENIX and STAR data. Wefound that the thermal predictions for the π gas, the resonance π gas and quark matter deviate, respectively,from the corresponding dynamical simulations from the JPCIAE model. The discrepancies were also foundbetween the π charge fluctuations and the charge fluctuations of all species of hadrons. However the chargefluctuations for "π from ρ and ω decay" and for all the hadrons from resonance decay are close to each other,indicating the correlation between positively and negatively charged hadrons is not sensitive to the species ofhadrons. This work shows further that it is questionable to use the charge fluctuations as a signature of QGP.

  3. Application of the Non-extensive Statistical Approach to High Energy Particle Collisions

    CERN Document Server

    Bíró, Gábor; Biró, Tamás Sándor; Ürmössy, Károly

    2016-01-01

    In high-energy collisions the number of the created particles is far less than the thermodynamic limit, especially in small colliding systems (e.g. proton-proton). Therefore final-state effects and fluctuations in the one-particle energy distribution are appreciable. As a consequence the characterization of identified hadron spectra with the Boltzmann\\,--\\,Gibbs thermodynamical approach is insufficient. Instead particle spectra measured in high-energy collisions can be described very well with Tsallis\\,--\\,Pareto distributions, derived from non-extensive thermodynamics. Using the Tsallis q-entropy formula, a generalization of the Boltzmann\\,--\\,Gibbs entropy, we interpret the microscopical physics by analysing the Tsallis $q$ and $T$ parameters. In this paper we give a quick overview on these parameters, analyzing identified hadron spectra from recent years in a wide center of mass energy range. We demonstrate that the fitted Tsallis-parameters show dependency on this energy and on the particle species. Our f...

  4. Maps of zeros of truncated generating functions in high energy collisions

    CERN Document Server

    Brambilla, M; Ugoccioni, R

    2006-01-01

    Theorems on zeros of the truncated generating functions in the complex plane are reviewed and applied to the class of power series distributions. These results, when scrutinized in the framework of the truncated generating function of NB (Pascal) MD type, lead to maps of zeros which are different in correspondence to different classes of events in pp collisions at LHC c.m. energies.

  5. Energy and Centrality Dependences of Charged Multiplicity Density in Relativistic Nuclear Collisions

    Institute of Scientific and Technical Information of China (English)

    SA; Ben-hao; Bonasera; A; TAI; An

    2002-01-01

    Using a hadron and string cascade model, JPCIAE, the energy and centrality dependences of chargedparticle pseudo rapidity density in relativistic nuclear collisions were studied. Within the framework ofthis model, both the relativistic p + p experimental data and the PHOBOS and PHENIX Au + Au data at

  6. New method to detect rotation in high-energy heavy-ion collisions

    OpenAIRE

    Csernai, Laszlo; Svelle, Sindre; Wang, Du-Juan

    2014-01-01

    With increasing beam energies the angular momentum of the fireball in peripheral heavy-ion collisions increases, and the proposed differential Hanbury Brown and Twiss analysis is able to estimate this angular momentum quantitatively. The method detects specific space-time correlation patterns, which are connected to rotation.

  7. Photon and dilepton production in high-energy heavy-ion collisions

    Indian Academy of Sciences (India)

    Takao Sakaguchi

    2015-05-01

    The recent results on direct photons and dileptons in high-energy heavy-ion collisions, obtained particularly at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) are reviewed. The results are new not only in terms of the probes, but also in terms of the precision. We shall discuss the physics learned from the results.

  8. LHC collision event at CMS showing two high energy photons (CMS Higgs search)

    CERN Multimedia

    CMS Collaboration

    2011-01-01

    11sec animation of a Higgs->GammaGamma candidate in CMS. Real CMS proton-proton collision events in which two high energy photons (dashed orange lines and towers) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

  9. LHC collision event at CMS showing four high energy electrons (CMS Higgs search)

    CERN Multimedia

    CMS Collaboration

    2011-01-01

    11sec animation of a Higgs->ZZ->4e candidate in CMS. Real CMS proton-proton collision events in which 4 high energy electrons (orange lines and towers) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

  10. LHC collision event at CMS showing four high energy muons (CMS Higgs search)

    CERN Multimedia

    CMS Collaboration

    2011-01-01

    11sec animation of a Higgs->ZZ->4mu candidate being created CMS . Real CMS proton-proton collision events in which 4 high energy muons (light blue lines) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

  11. Benefit of energy absorption by the truck in a frontal car-to-truck collision

    NARCIS (Netherlands)

    Coo, P.J.A. de; Adalian, C.

    2000-01-01

    EEVC Working Group 14 is investigating the effect of fixing energy absorbing front underrun protection systems (eaFUPS) to trucks instead of rigid devices in order to reduce the injury severity to car occupants in car-to-truck frontal collisions. Three car-to-truck crash tests with cars from

  12. Transverse momentum and transverse mass distributions of charged hadrons produced in Au-Au collisions at high energies

    Institute of Scientific and Technical Information of China (English)

    Liu Fu-Hu

    2008-01-01

    The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus-nucleus collisions at high energies are described by using a two-cylinder model. The results calculated by the model are compared and found to be in agreement with the experimental data of the STAR and E895 Collaborations, measured in Au-Au collisions at the relativistic heavy ion collider (RHIC) and alternating-gradient synchrotron (AGS) energies, respectively. In the energy range concerned, the excitation degree of emission source close to the central axis of cylinders increases obviously with the collision centrality and incident energy increasing, but it does not show any obvious change with the increase of the (pseudo) rapidity in central collisions. The excitation degree of emission source close to the side-surface of cylinders does not show any obvious change with the collision centrality, the (pseudo) rapidity, and the incident energy increasing.

  13. Energy loss in grazing proton-surface collisions

    Energy Technology Data Exchange (ETDEWEB)

    Juaristi, J.I. (Dept. Fisica de Materiales, Facultad de Quimicas, UPV/EHU, San Sebastian (Spain)); Garcia de Abajo, F.J. (Dept. Ciencias de la Computacion e Inteligencia Artificial, Facultad de Informatica, UPV/EHU, San Sebastian (Spain))

    1994-05-01

    The energy loss of fast protons, with energy E > 100 keV, specularly reflected on a solid surface with glancing angle of incidence of the order of a mrad is analysed on theoretical grounds. Two different contributions can be distinguished: (i) energy losses originating from the interaction with the valence band, accounted for through an induced force, and (ii) the excitation of electron bound states of the target atoms. The results are compared with available experimental data. (orig.)

  14. Energy Dependence of Pion and Kaon Production in Central Pb+Pb Collisions

    CERN Document Server

    Afanasiev, S V; Barna, D; Bartke, Jerzy; Barton, R A; Behler, M; Betev, L; Bialkowska, H; Billmeier, A; Blume, C; Blyth, C O; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Brun, R; Buncic, P; Cerny, V; Cramer, J G; Csató, P; Dinkelaker, P; Eckhardt, V; Filip, P; Fodor, Z; Foka, P Y; Freund, P; Friese, V; Gál, J; Gazdzicki, M; Georgopoulos, G; Gladysz-Dziadus, E; Hegyi, S; Höhne, C; Igo, G; Jones, P G; Kadija, K; Karev, A; Kolesnikov, V I; Kollegger, T; Kowalski, M; Kraus, I; Kreps, M; Van Leeuwen, M; Lévai, Peter; Malakhov, A I; Margetis, S; Markert, C; Mayes, B W; Melkumov, G L; Mischke, A; Molnár, J; Nelson, J M; Pálla, G; Panagiotou, A D; Perl, K; Petridis, A; Pikna, M; Pinsky, L; Pühlhofer, F; Reid, J G; Renfordt, R E; Retyk, W; Roland, C; Roland, G; Rybicki, A; Sammer, T; Sandoval, A; Sann, H; Schmitz, N; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Squier, G T A; Stock, Reinhard; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Trainor, T A; Varga, D; Vassiliou, Maria; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Whitten, C; Yoo, I K; Zaranek, J; Zimányi, J

    2002-01-01

    Results on the energy dependence of charged pion and kaon production in central Pb+Pb collisions at 40, 80 and 158 A GeV are presented and compared with data at lower and higher energies. The mean pion multiplicity increases approximately linearly with s^{1/4} with a change of slope around 40 A GeV. The change from pion suppression with respect to p+p interactions, as observed at low collision energies, to pion enhancement at high energies also occurs at about 40 A GeV. A non-monotonic energy dependence of the ratio of K+ to pi+ yields is observed, with a maximum close to 40 A GeV, followed by a nearly constant value at higher energies. The measured dependences are consistent with the hypothesis, derived within a Statistical Model of the Early Stage of nucleus-nucleus reactions, that a transient state of deconfined matter is created in Pb+Pb collisions for energies larger than about 40 A GeV.

  15. Proton structure in high-energy high-multiplicity p-p collisions

    CERN Document Server

    Glazek, Stanislaw D

    2016-01-01

    A few-body proton image, expected to be derivable from QCD in the renormalization group procedure for effective particles, is used within the Monte Carlo Glauber model to calculate the anisotropy coefficients in the initial collision-state of matter in high-energy high-multiplicity proton-proton interaction events. We estimate the ridge-like correlations in the final hadronic state by assuming their proportionality to the initial collision-state anisotropy. In our estimates, some distinct few-body proton structures appear capable of accounting for the magnitude of p-p ridge effect, with potentially discernible differences in dependence on multiplicity.

  16. Magnetic field effect on charmonium formation in high energy nuclear collisions

    Directory of Open Access Journals (Sweden)

    Xingyu Guo

    2015-12-01

    Full Text Available It is important to understand the strong external magnetic field generated at the very beginning of heavy ion collisions. We study the effect of the magnetic field on the anisotropic charmonium formation in Pb+Pb collisions at the LHC energy. The time dependent Schrödinger equation is employed to describe the motion of cc¯ pairs. We compare our model prediction of the non-collective anisotropic parameter v2 of J/ψ with CMS data at high transverse momentum.

  17. A surface hopping study of energy transfer in Na + Cd ∗* collisions

    Science.gov (United States)

    Angeli, Celestino; Granucci, Giovanni; Persico, Maurizio

    1996-06-01

    We have computed the cross sections for energy transfer and intramultiplet mixing in collisions between excited Cd and ground state Na atoms. Classical trajectories with surface hopping have been run on ab initio potentials, taking into account nonadiabatic and spin-orbit couplings. The theoretically determined cross sections contribute to identify the source of excited sodium atoms in heat pipe oven experiments with laser excitation of cadmium. The short lifetime of the collision complex leads to the conclusion that the three-body process Na + Cd∗* + M → NaCd∗* + M has a negligible role in the excimer production.

  18. Theorectical Studies of Excitation in Low-Energy Electron-Polyatomic Molecule Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Rescigno, T N; McCurdy, C W; Isaacs, W A; Orel, A E; Meyer, H D

    2001-08-13

    This paper focuses on the channeling of energy from electronic to nuclear degrees of freedom in electron-polyatomic molecule collisions. We examine the feasibility of attacking the full scattering problem, both the fixed-nuclei electronic problem and the post-collision nuclear dynamics, entirely from first principles. The electron-CO{sub 2} system is presented as an example. We study resonant vibrational excitation, showing how a6 initio, fixed-nuclei electronic cross sections can provide the necessary input for a multi-dimensional treatment of the nuclear vibrational dynamics.

  19. The Effects of Packaging on Collision Energy Absorption of Automotive Seat Headrest

    Directory of Open Access Journals (Sweden)

    Chen Minggang

    2016-01-01

    Full Text Available The automotive seat headrest plays an important role in the passenger protection during car crashes, and its structure parameters and performance have direct influence on the seat crashworthiness. In this paper, according to relevant regulations of GB11550-2009, collision simulation analyses of the seat headrest structure were carried out by Ls-dyna code. The law of different headrest packaging parameters on collision energy absorption was investigated to provide guidance for the headrest structure optimization design and improvement. The research results show that, with the increase of packaging of the headrest, the maximum acceleration and high acceleration duration time of head gradually decreases.

  20. Nuclear fragmentation energy and momentum transfer distributions in relativistic heavy-ion collisions

    Science.gov (United States)

    Khandelwal, Govind S.; Khan, Ferdous

    1989-01-01

    An optical model description of energy and momentum transfer in relativistic heavy-ion collisions, based upon composite particle multiple scattering theory, is presented. Transverse and longitudinal momentum transfers to the projectile are shown to arise from the real and absorptive part of the optical potential, respectively. Comparisons of fragment momentum distribution observables with experiments are made and trends outlined based on our knowledge of the underlying nucleon-nucleon interaction. Corrections to the above calculations are discussed. Finally, use of the model as a tool for estimating collision impact parameters is indicated.

  1. Tuning Charge Transfer in Ion-Surface Collisions at Hyperthermal Energies.

    Science.gov (United States)

    Yao, Yunxi; Giapis, Konstantinos P

    2016-05-18

    Charge exchange in ion-surface collisions may be influenced by surface adsorbates to alter the charge state of the scattered projectiles. We show here that the positive-ion yield, observed during ion scattering on metal surfaces at low incident energies, is greatly enhanced by adsorbing electronegative species onto the surface. Specifically, when beams of N(+) and O(+) ions are scattered off of clean Au surfaces at hyperthermal energies, no positive ions are observed exiting. Partial adsorption of F atoms on the Au surface, however, leads to the appearance of positively charged primary ions scattering off of Au, a direct result of the increase in the Au work function. The inelastic energy losses for positive-ion exits are slightly larger than the corresponding ionization energies of the respective N and O atoms, which suggest that the detected positive ions are formed by surface reionization during the hard collision event.

  2. Production mechanism of hot nuclei in violent collisions in the Fermi energy domain

    Science.gov (United States)

    Veselsky, M.

    2002-07-01

    A production mechanism of highly excited nuclei formed in violent collisions in the Fermi energy domain is investigated. The collision of two nuclei is decomposed into several stages which are treated separately. Simplified exciton concept is used for the description of pre-equilibrium emission. A modified spectator-participant scenario is used where motion along classical Coulomb trajectories is assumed. The participant and one of the spectator zones undergo incomplete fusion. Excitation energies of both cold and hot fragment are determined. Results of the calculation are compared to recent experimental data in the Fermi energy domain. Data on hot projectile-like, mid-velocity and fusion-like sources are described consistently. Geometric aspects of pre-equilibrium emission are revealed. Explanations to previously unexplained experimental phenomena are given. Energy deposited into non-thermal degrees of freedom is estimated.

  3. Transverse Momentum Distributions in proton - proton Collisions at LHC Energies and Tsallis Thermodynamics

    CERN Document Server

    AUTHOR|(CDS)2071357; Cleymans, J

    2014-01-01

    A detailed study of the transverse momentum distributions of charged particles produced in proton - proton collisions at LHC energies is presented. This is done using a thermodynamically consistent form of the Tsallis distribution. All variables used are thermodynamical and in particular, the temperature $T$ follows from the standard thermodynamic definition as being the derivative of the energy with respect to the (Tsallis) entropy. The momentum distribution of the final state particles obtained describe the transverse momentum distributions very well. The values of the parameters are determined from measurements by the ALICE, ATLAS and CMS collaborations and are discussed in detail. In particular, the Tsallis parameter, $q$ is found with consistent values for all the transverse momentum distributions despite large differences in kinematic regions and shows a slight increase with beam energy, reaching a value of 1.15 at 7 TeV. It is concluded that the hadronic system created in high-energy p - p collisions c...

  4. Kadomtsev-Petviashvili solitons propagation in a plasma system with superthermal and weakly relativistic effects

    Energy Technology Data Exchange (ETDEWEB)

    Hafeez-Ur-Rehman; Mahmood, S. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Department of Physics and Applied Mathematics, PIEAS, Nilore, 44000 Islamabad (Pakistan); Shah, Asif; Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan)

    2011-12-15

    Two dimensional (2D) solitons are studied in a plasma system comprising of relativistically streaming ions, kappa distributed electrons, and positrons. Kadomtsev-Petviashvili (KP) equation is derived through the reductive perturbation technique. Analytical solution of the KP equation has been studied numerically and graphically. It is noticed that kappa parameters of electrons and positrons as well as the ions relativistic streaming factor have an emphatic influence on the structural as well as propagation characteristics of two dimensional solitons in the considered plasma system. Our results may be helpful in the understanding of soliton propagation in astrophysical and laboratory plasmas, specifically the interaction of pulsar relativistic wind with supernova ejecta and the transfer of energy to plasma by intense electric field of laser beams producing highly energetic superthermal and relativistic particles [L. Arons, Astrophys. Space Sci. Lib. 357, 373 (2009); P. Blasi and E. Amato, Astrophys. Space Sci. Proc. 2011, 623; and A. Shah and R. Saeed, Plasma Phys. Controlled Fusion 53, 095006 (2011)].

  5. The dispersion relations of dispersive Alfvén waves in superthermal plasmas

    Science.gov (United States)

    Gaelzer, Rudi; Ziebell, Luiz F.

    2014-12-01

    The effects of velocity distribution functions (VDFs) that exhibit a power law dependence on the high-energy tail have been the subject of intense research by the space plasma community. Such functions, known as superthermal or kappa distributions, have been found to provide a better fitting to the VDF measured by several spacecraft in the plasma environment of the solar wind. In the literature, the general treatment for waves excited by (bi-)Maxwellian plasmas is well established. However, for kappa distributions, either isotropic or anisotropic, the wave characteristics have been studied mostly for the limiting cases of purely parallel or perpendicular propagation. Contributions for the general case of obliquely propagating waves have been scarcely reported so far. In this work we introduce a mathematical formalism that provides expressions for the dielectric tensor components and subsequent dispersion relations for oblique propagating dispersive Alfvén waves (DAWs) resulting from a kappa VDF. We employ an isotropic distribution, but the methods used here can be easily applied to more general anisotropic distributions, such as the bi-kappa or product-bi-kappa. The effect of the kappa index and thermal corrections on the dispersion relations of DAW is discussed.

  6. The second generation superthermal Ultra-Cold Neutron Source at RCNP

    Science.gov (United States)

    Pierre, Edgard; Masuda, Yasuhiro; Kawasaki, Shinsuke; Jeong, Sun Chan; Watanabe, Yutaka; Hatanaka, Kichiji; Matsumiya, Ryohei; Shin, Yun Chang; Matsuta, Kensaku; Mihara, Mototsugu

    2014-09-01

    The project of a second generation superthermal ultra-cold neutron (UCN) source is currently going on at RCNP, Osaka University, Japan. It is aiming to produce the world's highest density of polarized UCNs using down-scattering of spallation-produced and moderated cold neutrons in superfluid helium (He-II) at 0.6 K. This project is developed in collaboration between KEK (Tsukuba, Japan) and RCNP. The first generation UCN source was using a vertical extraction and was optimized from 2002 to 2012 to increase its density of UCN from 0.7 UCN/cc to 26 UCN/cc. We have built a second generation UCN source which use a horizontal extraction system thanks to the energy boost induced by the field of a superconducting polarizer magnet (SCM). The SCM allows only one spin state to pass through, which make our UCN source a source of polarized UCN. Polarization is kept thanks to new UCN guides. The first experimental results, the performances and the future improvements of this second generation source will be presented in this talk.

  7. Direct experimental evidence of non-equilibrium energy sharing in dissipative collisions

    CERN Document Server

    Casini, G; Olmi, A; Bini, M; Calamai, S; Meucci, F; Pasquali, G; Poggi, G; Stefanini, A A; Gobbi, A; Hildenbrand, K D

    1996-01-01

    Primary and secondary masses of heavy reaction products have been deduced from kinematics and E-ToF measurements, respectively, for the direct and reverse collisions of 100Mo with 120Sn at 14.1 A MeV. Direct experimental evidence of the correlation of energy-sharing with net mass transfer and model-independent results on the evolution of the average excitation from equal-energy to equal-temperature partition are presented.

  8. Effects of collision energy on stereodynamical information of the reaction F + HI → FI + H

    Indian Academy of Sciences (India)

    Jian-Jun Ma

    2015-09-01

    The vector correlations between products and reactants for the reaction F + HI → FI + H are studied using quasi-classical trajectory (QCT) method. Employing a semiempirical LEPS potential energy surface constructed by Kornweitz and Persky, this work calculates the angular distributions of (r), (r) and several PDDCSs in the center of mass frame. The effect of the collision energy on the product vector properties is also discussed.

  9. Search for Fractionally Charged Nuclei in High-Energy Oxygen-Lead Collisions

    CERN Multimedia

    2002-01-01

    We propose to use stacks of CR-39 plastic track detectors to look for fractionally charged projectile fragments produced in collisions of high-energy oxygen, sulfur, and calcium nuclei with a lead target. The expected charge resolution is @s^z~=~0.06e for fragments with 17e/3~@$<$~Z~@$<$~23e/3. We request that two target + stack assemblies be exposed to 1~x~10|5 oxygen nuclei at maximum available energy.

  10. $\\Lambda$ polarization in peripheral collisions at moderate relativistic energies

    CERN Document Server

    Xie, Y L; Stöcker, H; Wang, D J; Csernai, L P

    2016-01-01

    The polarization of $\\Lambda$ hyperons from relativistic flow vorticity is studied in peripheral heavy ion reactions at FAIR and NICA energies, just above the threshold of the transition to the Quark-Gluon Plasma. Previous calculations at higher energies with larger initial angular momentum, predicted significant $\\Lambda$ polarization based on the classical vorticity term in the polarization, while relativistic modifications decreased the polarization and changed its structure in the momentum space. At the lower energies studied here, we see the same effect namely that the relativistic modifications decrease the polarization arising from the initial shear flow vorticity.

  11. Longitudinal scaling of net-protons in AuAu and pp collisions at RHIC energies

    Science.gov (United States)

    Videbaek, Flemming

    2008-10-01

    BRAHMS has studied net-protons distributions in Au+Au and p+p collisions at √sNN=62.4 and 200 GeV. Net-proton distributions reflect the net-baryon yields and can be used to extract the nuclear stopping in the collisions, thus providing information on baryon number transport and energy available for particle production. The talk will present final and preliminary results from the above mentioned systems. It will be shown that in p+p and in Au+Au central collisions that net-proton distributions exhibit longitudinal scaling once the target contribution to the projectile rapidity range is corrected for. The difference between p+p and Au+Au will be discussed. Aspects of future measurements at the LHC of net-baryons at mid-rapidity will be brought forth.

  12. LOCAL COLLISION SIMULATION OF AN SC WALL USING ENERGY ABSORBING STEEL

    Directory of Open Access Journals (Sweden)

    CHUL-HUN CHUNG

    2013-08-01

    Full Text Available This study evaluates the local damage of a turbine in an auxiliary building of a nuclear power plant due to an external impact by using the LS-DYNA finite element program. The wall of the auxiliary building is SC structure and the material of the SC wall plate is high manganese steel, which has superior ductility and energy absorbance compared to the ordinary steel used for other SC wall plates. The effects of the material of the wall, collision speed, and angle on the magnitude of the local damage were evaluated by local collision analysis. The analysis revealed that the SC wall made of manganese steel had significantly less damage than the SC wall made of ordinary steel. In conclusion, an SC wall made of manganese steel can have higher effective resistance than an SC wall made of ordinary steel against the local collision of an airplane engine or against a turbine impact.

  13. Propagation of Fluctuations in Au+Au Collisions at FAIR energy

    CERN Document Server

    Ahmad, S; Bashir, S; jahan, H; Ahmad, N; Chattopadhyay, S

    2014-01-01

    Event by event fluctuations of particle multiplicities and their ratios are considered to be sensitive probes to the exotic phenomena in high energy heavy ion collisions like phase transtion or the occurence of critical point. These phenomena might take place at different time after the collision based on fulfilling the required conditions at a particular time. Fluctuations are therefore expected to show non-monotonic behaviour at the of time of occurence of these phenomena. Experimentally, fluctuations are measured at freezeout. In this work, using the hybrid version of the UrQMD event generator, we have investigated the propagation of fluctuations of particle multiplicities, their ratios and the ratio of total positive and negative charges in AuAu collisions at E_{lab} < 90 AGeV. Two commonly used experimental measures i.e., {\\sigma^2}/mean and {\

  14. Molecular (Feshbach) treatment of charge exchange Li/sup 3 +/+He collisions. I. Energies and couplings

    Energy Technology Data Exchange (ETDEWEB)

    Martin, F.; Riera, A.; Yanez, M.

    1986-05-15

    We point out a fundamental difference between the molecular treatment of charge exchange X/sup n/++H(1s) and X/sup n/++He(1s/sup 2/) collisions, which is that the latter process involves molecular states that are formally autoionizing. Then standard ab initio methods do not, in general, yield the relevant wave functions that are needed in the collision treatment, irrespective of whether quasimolecular autoionization be significant or not during the collision. We implement a particularly simple and useful form of the Feshbach formalism to calculate the energies of those two electron systems, and a method to evaluate the corresponding dynamical couplings is presented for the first time. Our implementation of this formalism together with the new computational techniques involved are presented in detail.

  15. Isospin dependence of balance energy in heavy-ion collisions

    CERN Document Server

    Kaur, Varinderjit; Kumar, Suneel

    2011-01-01

    Based on the isospin-dependent quantum molecular dynamics (IQMD) picture, we attempt to understand the nature of transverse flow in $_{28}Ni^{58}+_{28}Ni^{58}$ and $_{26}Fe^{58}+_{26}Fe^{58}$ systems at wide range of energies and impact parameters. The isospin dependence of balance energy in transverse flow is clearly visible. The results are compared with the experimental data available.

  16. Centrality categorization for R_{p(d)+A} in high-energy collisions

    CERN Document Server

    Adare, A; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Angerami, A; Aoki, K; Apadula, N; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Bhom, J H; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Caringi, A; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; del Valle, Z Conesa; Connors, M; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Jr., \\,; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Grim, G; Perdekamp, M Grosse; Gunji, T; Gustafsson, H -Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D J; Kim, E -J; Kim, Y -J; Kinney, E; Kiss, Á; Kistenev, E; Kleinjan, D; Kochenda, L; Komkov, B; Konno, M; Koster, J; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Li, X; Lichtenwalner, P; Liebing, P; Levy, L A Linden; Liška, T; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; Means, N; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Milov, A; Mitchell, J T; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Koop, J D Orjuela; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J -C; Pereira, H; Perepelitsa, D; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Seto, R; Sharma, D; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhou, S

    2013-01-01

    High-energy proton- and deuteron-nucleus collisions provide an excellent tool for studying a wide array of physics effects, including modifications of parton distribution functions in nuclei, gluon saturation, and color neutralization and hadronization in a nuclear environment, among others. All of these effects are expected to have a significant dependence on the size of the nuclear target and the impact parameter of the collision, also known as the collision centrality. In this article, we detail a method for determining centrality classes in p(d)+A collisions via cuts on the multiplicity at backward rapidity (i.e., the nucleus-going direction) and for determining systematic uncertainties in this procedure. For d+Au collisions at sqrt(s_NN) = 200 GeV we find that the connection to geometry is confirmed by measuring the fraction of events in which a neutron from the deuteron does not interact with the nucleus. As an application, we consider the nuclear modification factors R_{p(d)+A}, for which there is a po...

  17. The effect of translational energy on collision-induced dissociation of highly excited NO 2 on MgO(100)

    Science.gov (United States)

    Arnold, D. W.; Korolik, M.; Wittig, C.; Reisler, H.

    1998-01-01

    Collision-induced dissociation of highly excited NO 2 (i.e., mixed 2B 2/ 2A 1 molecular eigenstates just below D0) impinging on MgO(100) surfaces has been studied as a function of NO 2 internal excitation at an incident translational energy of 4400 cm -1 by using state-selective NO detection. NO internal energy distributions as well as the average energy transferred per activating collision have been obtained. The results, in particular the NO [ 2Π 1/2]/[ 2Π 3/2] population ratios, indicate the presence of exit-channel interactions with the surface that are dependent on collision energy.

  18. Charged particle multiplicity and transverse energy distribution using Weibull-Glauber approach in heavy-ion collisions

    CERN Document Server

    Behera, Nirbhay K; Naik, Bharati; Nandi, Basanta K; Pani, Tanmay

    2016-01-01

    The charged particle multiplicity distribution and the transverse energy distribution measured in heavy-ion collisions at top RHIC and LHC energies are described using the two-component model approach based on convolution of Monte Carlo Glauber model with the Weibull model for particle production. The model successfully describes the multiplicity and transverse energy distribution of minimum bias collision data for a wide range of energies. We also propose that Weibull-Glauber model can be used to determine the centrality classes in heavy-ion collision as an alternative to the conventional Negative Binomial distribution for particle production.

  19. Microscopic Calculation of Pre-Compound Excitation Energies for Heavy-Ion Collisions

    OpenAIRE

    2009-01-01

    We introduce a microscopic approach for calculating the excitation energies of systems formed during heavy-ion collisions. The method is based on time-dependent Hartree-Fock (TDHF) theory and allows the study of the excitation energy as a function of time or ion-ion separation distance. We discuss how this excitation energy is related to the estimate of the excitation energy using the reaction $Q$-value, as well as its implications for dinuclear pre-compound systems formed during heavy-ion co...

  20. Dominant wing spectroscopy of energy pooling collisions near the boundary layer involving thermal caesium vapour

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We have observed the dominant wing spectroscopy of energy pooling collision near the boundary layer involving Cs atoms under the condition of moderate-to-high optical depths at line-centre. It appears from our experimental investigations that the energy-pooling fluorescence presents about 16 spectral lines, and all the lines can be assigned to the Cs atomic transitions. We find that all lines of the energy-pooling retrofluorescence from the heated Cs atomic vapour cell show two-peak profiles. In addition, its pumping power linear dependence in the energy pooling process has been measured and analysed.

  1. Revisiting the thermal and superthermal two-class distribution of incomes. A critical perspective

    Science.gov (United States)

    Schneider, Markus P. A.

    2015-01-01

    This paper offers a two-pronged critique of the empirical investigation of the income distribution performed by physicists over the past decade. Their finding rely on the graphical analysis of the observed distribution of normalized incomes. Two central observations lead to the conclusion that the majority of incomes are exponentially distributed, but neither each individual piece of evidence nor their concurrent observation robustly proves that the thermal and superthermal mixture fits the observed distribution of incomes better than reasonable alternatives. A formal analysis using popular measures of fit shows that while an exponential distribution with a power-law tail provides a better fit of the IRS income data than the log-normal distribution (often assumed by economists), the thermal and superthermal mixture's fit can be improved upon further by adding a log-normal component. The economic implications of the thermal and superthermal distribution of incomes, and the expanded mixture are explored in the paper.

  2. Small amplitude Kinetic Alfven waves in a superthermal electron-positron-ion plasma

    Science.gov (United States)

    Adnan, Muhammad; Mahmood, Sahahzad; Qamar, Anisa; Tribeche, Mouloud

    2016-11-01

    We are investigating the propagating properties of coupled Kinetic Alfven-acoustic waves in a low beta plasma having superthermal electrons and positrons. Using the standard reductive perturbation method, a nonlinear Korteweg-de Vries (KdV) type equation is derived which describes the evolution of Kinetic Alfven waves. It is found that nonlinearity and Larmor radius effects can compromise and give rise to solitary structures. The parametric role of superthermality and positron content on the characteristics of solitary wave structures is also investigated. It is found that only sub-Alfvenic and compressive solitons are supported in the present model. The present study may find applications in a low β electron-positron-ion plasma having superthermal electrons and positrons.

  3. Investigation of a superthermal ultracold neutron source based on a solid deuterium converter for the TRIGA Mainz reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lauer, Thorsten

    2010-12-22

    Research in fundamental physics with the free neutron is one of the key tools for testing the Standard Model at low energies. Most prominent goals in this field are the search for a neutron electric dipole moment (EDM) and the measurement of the neutron lifetime. Significant improvements of the experimental performance using ultracold neutrons (UCN) require reduction of both systematic and statistical errors.The development and construction of new UCN sources based on the superthermal concept is therefore an important step for the success of future fundamental physics with ultracold neutrons. Significant enhancement of today available UCN densities strongly correlates with an efficient use of an UCN converter material. The UCN converter here is to be understood as a medium which reduces the velocity of cold neutrons (CN, velocity of about 600 m/s) to the velocity of UCN (velocity of about 6 m/s).Several big research centers around the world are presently planning or constructing new superthermal UCN sources, which are mainly based on the use of either solid deuterium or superfluid helium as UCN converter.Thanks to the idea of Yu.Pokotilovsky, there exists the opportunity to build competitive UCN sources also at small research reactors of the TRIGA type. Of course these smaller facilities don't promise high UCN densities of several 1000 UCN/cm{sup 3}, but they are able to provide densities around 100 UCN/cm{sup 3} for experiments.In the context of this thesis, it was possible to demonstrate succesfully the feasibility of a superthermal UCN source at the tangential beamport C of the research reactor TRIGA Mainz. Based on a prototype for the future UCN source at the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII) in Munich, which was planned and built in collaboration with the Technical University of Munich, further investigations and improvements were done and are presented in this thesis. In parallel, a second UCN source for the radial beamport D was

  4. Jet energy loss and bulk parton collectivity in nucleus-nucleus collisions at RHIC

    Institute of Scientific and Technical Information of China (English)

    HUANG Huan-Zhong

    2009-01-01

    Nucleus-nucleus collisions at RHIC produce high temperature and high energy density matter which exhibits paxtonic degrees of freedom. We will discuss measurements of nuclear modification factors for light hadrons and non-photonic electrons from heavy quark decays, which reflect the flavor dependence of energy loss of high momentum partons traversing the dense QCD medium. The dense QCD medium responds to energy loss of high momentum patrons in a pattern consistent with that expected from a hydrodynamic fluid. The hadronization of bulk partonic matter exhibits collectivity with effective partonic degrees of freedom. Nuclear collisions at RHIC provide an intriguing environment, where many constituent quark ingredients are readily available for possible formation of exotic particles through quark coalescence or recombinations.

  5. Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

    Science.gov (United States)

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bartoli, A.; Bini, M.; Casini, G.; Coppi, C.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Taccetti, N.; Vanzi, E.

    2006-09-01

    A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision, and mass of the system. The data have been collected with the FIASCO setup in the reactions Nb93+Nb93 at (17,23,30,38)A MeV and Sn116+Sn116 at (30,38)A MeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code GEMINI at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences in both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.

  6. Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies

    CERN Document Server

    Piantelli, S; Olmi, A; Bardelli, L; Bartoli, A; Bini, M; Casini, G; Coppi, C; Mangiarotti, A; Pasquali, G; Poggi, G; Stefanini, A A; Taccetti, N; Vanzi, E

    2006-01-01

    A systematic investigation of the average multiplicities of light charged particles and intermediate mass fragments emitted in peripheral and semiperipheral collisions is presented as a function of the beam energy, violence of the collision and mass of the system. The data have been collected with the "Fiasco" setup in the reactions 93Nb+93Nb at 17, 23, 30, 38AMeV and 116Sn+116Sn at 30, 38AMeV. The midvelocity emission has been separated from the emission of the projectile-like fragment. This last component appears to be compatible with an evaporation from an equilibrated source at normal density, as described by the statistical code Gemini at the appropriate excitation energy. On the contrary, the midvelocity emission presents remarkable differences for what concerns both the dependence of the multiplicities on the energy deposited in the midvelocity region and the isotopic composition of the emitted light charged particles.

  7. Axial anomaly and energy dependence of hyperon polarization in heavy-ion collisions

    Science.gov (United States)

    Sorin, Alexander; Teryaev, Oleg

    2017-01-01

    We address the issue of energy and charge dependence of global polarization of Λ hyperons in peripheral Au-Au collisions recently observed by the STAR Collaboration at Relativistic Heavy Ion Collider (RHIC). We compare different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of the gravitational anomaly contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with increasing collision energy. Our mechanism leads to polarization of Λ ¯ of the same sign and larger magnitude than the polarization of Λ. The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.

  8. Axial anomaly and energy dependence of hyperon polarization in Heavy-Ion Collisions

    CERN Document Server

    Sorin, A

    2016-01-01

    We address the issue of energy and charge dependence of global polarization of $\\Lambda$ hyperons in peripheral $Au-Au$ collisions recently observed by STAR collaboration at RHIC. We compare the different contributions to the anomalous mechanism relating polarization to vorticity and hydrodynamic helicity in QCD matter. We stress that the suppression of gravitational anomaly related contribution in strongly correlated matter observed in lattice simulations confirms our earlier prediction of rapid decrease of polarization with collision energy. Our mechanism leads to the polarization of $\\bar \\Lambda$ of the same sign and larger magnitude than $\\Lambda$. The energy and charge dependence of polarization is suggested as a sensitive probe of fine details of QCD matter structure.

  9. Measurements of low energy observables in proton-proton collisions with the ATLAS Detector

    CERN Document Server

    Foster, Andrew Geoffrey; The ATLAS collaboration

    2017-01-01

    Low energy phenomena have been studied in detail at the LHC, providing important input for improving models of non-perturbative QCD effects. The ATLAS collaboration has performed several new measurements in this sector: We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton- -proton collisions at a centre-of-mass energy of 13 TeV. The results are corrected for detector effects and compared to predictions from various Monte Carlo generators. In addition, we present studies on the correlated hadron production, as they are an important source for information on the early stages of hadron formation. In particular, an analysis of the momentum difference between charged hadrons in high–energy proton–proton collisions is performed in order to study coherent particle production. The results are compared to the predictions of a helical QCD string fragmenting model. ATLAS has also studied the production of neutral strange particles inside and outside li...

  10. Beam energy dependence of pseudorapidity distributions of charged particles produced in heavy-ion collisions at RHIC and LHC energies

    CERN Document Server

    Basu, Sumit; Datta, Kaustuv

    2016-01-01

    Heavy-ion collisions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN probe matter at extreme conditions of temperature and energy density. Most of the global properties of the collisions can be extracted from the measurements of charged particle multiplicity and pseudorapidity ($\\eta$) distributions. We have shown that the available experimental data on beam energy and centrality dependence of \\Eta-distributions in heavy-ion (Au+Au or Pb+Pb) collisions from \\sNN=7.7 GeV to 2.76 TeV are reasonably well described by the AMPT model, which is used for further exploration. The nature of the \\Eta-distributions has been described by a double Gaussian function using a set of fit parameters, which exhibit a regular pattern as a function of beam energy. By extrapolating the parameters to a higher energy of \\sNN~=~5.02 TeV, we have obtained the charged particle multiplicity densities, \\Eta-distributions and energy densities for various centralities. Incident...

  11. Statistical and dynamical aspects of intermediate energy nuclear collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ghetti, R.

    1997-01-01

    Studies of intermediate energy heavy ion reactions have revealed that the probability of emitting n-fragments is reducible to the probability of emitting a single fragment through the binomial distribution. The resulting one-fragment probability shows a dependence on the thermal energy that is characteristic of statistical decay. Similarly, the charge distributions associated with n-fragment emission are reducible to the one-fragment charge distribution, and thermal scaling is observed. The reducibility equation for the n-fragment charge distribution contains a quantity with a value that starts from zero, at low transverse energies, and saturates at high transverse energies. This evolution may signal a transition from a coexistence phase to a vapour phase. In the search for a signal of liquid-gas phase transition, the appearance of intermittency is reconsidered. Percolation calculations, as well as data analysis, indicate that an intermittent-like signal appears from classes of events that do not coincide with the critical one. 232 refs.

  12. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  13. The broad away side of azimuthal correlations: 3 vs 2 final state particles in high energy nuclear collisions

    CERN Document Server

    Ayala, Alejandro; Magnin, J; Ortiz, Antonio; Paic, G; Tejeda-Yeomans, Maria Elena

    2011-01-01

    In high energy heavy ion collisions at RHIC there are important aspects of the medium induced dynamics, that are still not well understood. In particular, there is a broadening and even a double hump structure of the away-side peak appearing in azimuthal correlation studies in Au+Au collisions which is absent in p+p collisions at the same energies. These features are already present but suppressed in p+p collisions: 2 to 3 parton processes produce such structures but are suppressed with respect to 2 to 2 processes. We argue that in A+A collisions the different geometry for the trajectories of 3 as opposed to 2 particles in the final state, together with the medium induced energy loss effects on the different cross sections, create a scenario that enhances processes with 3 particles in the final state, which gives on average this double hump structure.

  14. Accurate global potential energy surface for the H + OH+ collision

    Science.gov (United States)

    Gannouni, M. A.; Jaidane, N. E.; Halvick, P.; Stoecklin, T.; Hochlaf, M.

    2014-05-01

    We mapped the global three-dimensional potential energy surface (3D-PES) of the water cation at the MRCI/aug-cc-pV5Z including the basis set superposition (BSSE) correction. This PES covers the molecular region and the long ranges close to the H + OH+(X3Σ-), the O + H2+(X2Σg+), and the hydrogen exchange channels. The quality of the PES is checked after comparison to previous experimental and theoretical results of the spectroscopic constants of H2O+(tilde X2B1) and of the diatomic fragments, the vibronic spectrum, the dissociation energy, and the barrier to linearity for H2O+(tilde X2B1). Our data nicely approach those measured and computed previously. The long range parts reproduce quite well the diatomic potentials. In whole, a good agreement is found, which validates our 3D-PES.

  15. Calorimetry applied to nucleus-nucleus collisions at ultrarelativistic energies

    Energy Technology Data Exchange (ETDEWEB)

    Plasil, F.

    1988-01-01

    A general introduction to high-energy calorimetry is presented, together with brief descriptions of the two types of cascades relevant to calorimetric measurements. This is followed by a discussion of ''compensation'' and of the ''e/h'' ratio. A detailed description of two calorimeters designed and constructed for the CERN WA80 experiment are also given. 16 refs., 17 figs., 5 tabs.

  16. Near-resonant rotational energy transfer in HCl–H{sub 2} inelastic collisions

    Energy Technology Data Exchange (ETDEWEB)

    Lanza, Mathieu; Lique, François, E-mail: francois.lique@univ-lehavre.fr [LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058 Le Havre (France); Kalugina, Yulia [LOMC - UMR 6294, CNRS-Université du Havre, 25 rue Philippe Lebon, BP 540, 76058 Le Havre (France); Department of Optics and Spectroscopy, Tomsk State University, 36 Lenin av., Tomsk 634050 (Russian Federation); Wiesenfeld, Laurent [UJF-Grenoble 1/CNRS, Institut de Planétologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041 (France)

    2014-02-14

    We present a new four-dimensional (4D) potential energy surface for the HCl–H{sub 2} van der Waals system. Both molecules were treated as rigid rotors. Potential energy surface was obtained from electronic structure calculations using a coupled cluster with single, double, and perturbative triple excitations method. The four atoms were described using the augmented correlation-consistent quadruple zeta basis set and bond functions were placed at mid-distance between the HCl and H{sub 2} centers of mass for a better description of the van der Waals interaction. The global minimum is characterized by the well depth of 213.38 cm{sup −1} corresponding to the T-shape structure with H{sub 2} molecule on the H side of the HCl molecule. The dissociation energies D{sub 0} are 34.7 cm{sup −1} and 42.3 cm{sup −1} for the complex with para- and ortho-H{sub 2}, respectively. These theoretical results obtained using our new PES are in good agreement with experimental values [D. T. Anderson, M. Schuder, and D. J. Nesbitt, Chem. Phys. 239, 253 (1998)]. Close coupling calculations of the inelastic integral rotational cross sections of HCl in collisions with para-H{sub 2} and ortho-H{sub 2} were performed at low and intermediate collisional energies. Significant differences exist between para- and ortho-H{sub 2} results. The strongest collision-induced rotational HCl transitions are the transitions with Δj = 1 for collisions with both para-H{sub 2} and ortho-H{sub 2}. Rotational relaxation of HCl in collision with para-H{sub 2} in the rotationally excited states j = 2 is dominated by near-resonant energy transfer.

  17. Collision dynamics of He@C60+He@C60 at low energies

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

  18. Rotational energy transfer in collisions between CO and Ar at temperatures from 293 to 30 K

    Science.gov (United States)

    Mertens, Laura A.; Labiad, Hamza; Denis-Alpizar, Otoniel; Fournier, Martin; Carty, David; Le Picard, Sébastien D.; Stoecklin, Thierry; Sims, Ian R.

    2017-09-01

    Experimental measurements and theoretical calculations are reported for rotational energy transfer in the Ar-CO system. Experiments were performed in cold uniform supersonic flows of Ar, using an infrared - vacuum ultraviolet double resonance technique to measure absolute state-to-state rate constants and total relaxation cross sections for rotational energy transfer within the (v = 2) vibrational state of CO in collision with Ar at temperatures from 30.5 to 293 K. Close-coupling calculations were also performed using a recent potential energy surface (Sumiyoshi and Endo, 2015). Very good agreement is obtained between measured and calculated values.

  19. An Estimate of the Thermodynamic Pressure in High-Energy Collisions

    CERN Document Server

    Tawfik, Abdel Nasser

    2015-01-01

    We introduce a novel approach to estimate the thermodynamic pressure from heavy-ion collisions based on recently measured higher-order moments of particle multiplicities by the STAR experiment. We start with fitting the experimental results in the most-central collisions. Then, we integrate them back to lower ones. For example, we find that the first-order moment, the mean multiplicity, is exactly reproduced from the integral of variance, the second-order moment. Therefore, the zero-order moment, the thermodynamic pressure, can be estimated from the integral of the mean multiplicity. the possible comparison between such a kind of pressure (deduced from the integral of particle multiplicity) and the lattice pressure and the relating of Bjorken energy density to the lattice energy density are depending on lattice QCD at finite baryon chemical potential and first-principle estimation of the formation time of the quark-gluon plasma (QGP).

  20. Quantum calculations of H2-H2 collisions: from ultracold to thermal energies

    CERN Document Server

    Quéméner, Goulven

    2008-01-01

    We present quantum dynamics of collisions between two para-H2 molecules from low (1 mK) to high collision energies (1 eV). The calculations are carried out using a quantum scattering code that solves the time-independent Schrodinger equation in its full dimensionality without any decoupling approximations. The six-dimensional potential energy surface for the H4 system developed by Boothroyd et al. [J. Chem. Phys. 116, 666 (2002)] is used in the calculations. Elastic, inelastic and state-to-state cross sections as well as rate coefficients from T = 1 K to 400 K obtained from our calculations are compared with available experimental and theoretical results. Overall, good agreement is obtained with previous studies.

  1. Collision energy dependence of He and Ne capture by C sup + sub 60

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, E.E.B.; Ehlich, R.; Hielscher, A.; Frazao, J.M.A.; Hertel, I.V. (Freiburg Univ. (Germany). Fakultaet fuer Physik Freiburg Univ. (Germany). Freiburger Materialforschungszentrum (FMF))

    1992-04-01

    Recently, reports of the formation of endohedral cluster compounds He{alpha}C{sup +}{sub n} and Ne{alpha}C{sup +}{sub n-4} (n even and {<=}60) have been published for high energy collisions between C{sup +}{sub 60} and rare gases. Here we present the collision energy dependence for the formation of He{alpha}C{sup +}{sub 60} and Ne{alpha}C{sup +}{sub 60} in the region of the energetic threshold for the capture process. The threshold for He capture lies at 6{+-}2 eV in the centre of mass reference frame whereas that for Ne lies somewhat higher at 9{+-}1 eV. ({alpha} means endohedral fulleren compounds.) (orig.).

  2. Two-Pion Interferometry for the Granular Source in Heavy Ion Collisions at LHC Energies

    Institute of Scientific and Technical Information of China (English)

    尹洪杰; 安飞; 张卫宁

    2012-01-01

    The space-time characters of the pion-emitting sources produced in the heavy ion collisions at the Large Hadron Collider (LHC) energies are investigated in a granular source model of quark-gluon plasma droplets. The results of two-pion interferometry indicate that the longi- tudinal interferometry radius is sensitive to the initial breakup time of the system. For a larger breakup time the values of the longitudinal interferometry radius for the LHC source are larger than that of the source produced in the collisions at the Relativistic Heavy Ion Collider's (RHIC) top energy. However, the values of the longitudinal radius are smaller if the source fragments at a smaller breakup time with a higher initial temperature of the droplets. The values of the transverse interferometry radius in the "side" direction for the LHC sources are larger than those for the RHIC source. The imaging analyses for the characteristic quantities of the granular sources are consistent with the interferometry radii.

  3. On Extraction of Chemical Potentials of Quarks from Particle Transverse Momentum Spectra in High Energy Collisions

    Directory of Open Access Journals (Sweden)

    Hong Zhao

    2015-01-01

    Full Text Available We present two methods to extract the chemical potentials of quarks in high energy collisions. The first method is based on the ratios of negatively/positively charged particles, and the temperatures extracted from the transverse momentum spectra of related hadrons are needed. The second method is based on the chemical potentials of some particles, and we also need the transverse momentum spectra of related hadrons. To extract the quark chemical potentials, we would like to propose experimental collaborations to measure simultaneously not only the transverse momentum spectra of p-, p, K-, K+, π-, and π+, but also those of D-, D+, B-, and B+ (even those of Δ++, Δ-, and Ω- in high energy nuclear collisions.

  4. Jets and produced particles in pp collisions from SPS to RHIC energies for nuclear applications

    CERN Document Server

    Barnafoldi, G G; Lévai, Peter; Papp, G; Zhang, Y

    2001-01-01

    Higher-order pQCD corrections play an important role in the reproduction of data at high transverse momenta in the energy range 20 GeV $ \\leq \\sqrt{s} \\leq 200$ GeV. Recent calculations of photon and pion production in $pp$ collisions yield detailed information on the next-to-leading order contributions. However, the application of these results in proton-nucleus and nucleus-nucleus collisions is not straightforward. The study of nuclear effects requires a simplified understanding of the output of these computations. Here we summarize our analysis of recent calculations, aimed at handling the NLO results by introducing process and energy-dependent $K$ factors.

  5. Formation of hypernuclei in heavy-ion collisions around the threshold energies

    CERN Document Server

    Botvina, A S; Steinheimer, J; Bleicher, M; Pochodzalla, J

    2016-01-01

    In relativistic ion collisions there are excellent opportunities to produce and investigate hyper-nuclei. We have systematically studied the formation of hypernuclear spectator residues in peripheral heavy-ion collisions with the transport DCM and UrQMD models. The hyperon capture was calculated within the potential and coalescence approaches. We demonstrate that even at the beam energies around and lower than the threshold for producing Lambda hyperons in binary nucleon-nucleon interactions a considerable amount of hypernuclei, including multi-strange ones, can be produced. This is important for preparation of new experiments on hypernuclei in the wide energy range. The uncertainties of the predictions are investigated within the models, and the comparison with the strangeness production measured in experiments is also performed.

  6. The Theory of High Energy Collision Processes - Final Report DOE/ER/40158-1

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tai, T.

    2011-09-15

    In 1984, DOE awarded Harvard University a new Grant DE-FG02-84ER40158 to continue their support of Tai Tsun Wu as Principal Investigator of research on the theory of high energy collision processes. This Grant was renewed and remained active continuously from June 1, 1984 through November 30, 2007. Topics of interest during the 23-year duration of this Grant include: the theory and phenomenology of collision and production processes at ever higher energies; helicity methods of QED and QCD; neutrino oscillations and masses; Yang-Mills gauge theory; Beamstrahlung; Fermi pseudopotentials; magnetic monopoles and dyons; cosmology; classical confinement; mass relations; Bose-Einstein condensation; and large-momentum-transfer scattering processes. This Final Report describes the research carried out on Grant DE-FG02-84ER40158 for the period June 1, 1984 through November 30, 2007. Two books resulted from this project and a total of 125 publications.

  7. Can dissipation prevent explosive decomposition in high-energy heavy ion collisions?

    CERN Document Server

    Fraga, E S; Fraga, Eduardo S.

    2005-01-01

    We discuss the role of dissipation in the explosive spinodal decomposition scenario of hadron production during the chiral transition after a high-energy heavy ion collision. We use a Langevin description inspired by microscopic nonequilibrium field theory results to perform real-time lattice simulations of the behavior of the chiral fields. We show that the effect of dissipation can be dramatic. Analytic results for the short-time dynamics are also presented.

  8. Baryonic Effect on XcJ Suppression in Au+Au Collisions at RHIC Energies

    Institute of Scientific and Technical Information of China (English)

    PENG Ru; XU Xiao-Ming; ZHOU Dai-Cui

    2004-01-01

    @@ We predict that xcJ mesons at low transverse momentum in the central rapidity region are almost dissociated by nucleons and antinucleons in hadronic matter produced in central Au+Au collisions at relativistic high-ion collider (RHIC) energies √SNN = 130 and 200 GeV. In the calculations the nucleon and antinucleon distributions in hadronic matter are results of evolution from their freeze-out distributions which well fit the experimental transverse momentum spectra of proton and antiproton.

  9. GenEx: A simple generator structure for exclusive processes in high energy collisions

    CERN Document Server

    Kycia, R A; Staszewski, R; Turnau, J

    2014-01-01

    A simple C++ class structure for construction of a Monte Carlo event generators which can produce unweighted events within relativistic phase space is presented. The generator is self-adapting to the provided matrix element and acceptance cuts. The program is designed specially for exclusive processes and includes, as an example of such an application, implementation of the model for exclusive production of meson pairs $pp \\rightarrow p M^+M^- p $ in high energy proton-proton collisions.

  10. Calculations for populations of selected isotopes in intermediate energy heavy ion collisions

    CERN Document Server

    Majumder, A

    2000-01-01

    We compute the populations of isotopes of Boron, Carbon and Nitrogen measured experimentally in intermediate energy heavy ion collisions. A two component soluble statistical model is used to find the initial populations of different nuclei at a finite temperature. These initial populations are both in particle stable and particle unstable states. The particle unstable states then decay. The final populations after these decays are computed and compared with experimental data.

  11. Collisions near Kerr black holes: lower limit of energy between orbiting and incoming particles

    Science.gov (United States)

    Rutkowski, Mieszko

    2017-01-01

    In our paper we investigate the lower limit of collisional energy of test particles near the Kerr black hole. In particular we examine the minimal Lorentz factor between the freely falling particles and the particles orbiting around a black hole. We consider collisions on the innermost stable circular orbit and examine near-extreme case, where collisions take place near an event horizon. By fine-tuning the particles' angular momentum, the Lorentz factor of the collision can always be minimized to a value dependent on the black hole's spin. We identified that this minimal value is always less than 2√{2}-1/√{3} and more than √{12}-1/√{6} (the limits are the values for an extreme Kerr and Schwarzschild, respectively). It implies that this kind of collisions of compact objects are expected to be highly energetic near supermassive black holes. In addition, we show that an interaction between black hole's and particle's spins has an influence on minimal Lorentz factor. This contribution is nonnegligible for near-extreme black holes. We also discuss the relation between our results and sci-fi movie Interstellar.

  12. Medium effects on heavy-flavour observables in high-energy nuclear collisions

    Science.gov (United States)

    Beraudo, Andrea

    2016-11-01

    The peculiar role of heavy-flavour observables in relativistic heavy-ion collisions is discussed. Produced in the early stage, c and b quarks cross the hot medium arising from the collision, interacting strongly with the latter, until they hadronize. Depending on the strength of the interaction heavy quarks may or not approach kinetic equilibrium with the plasma, tending in the first case to follow the collective flow of the expanding fireball. The presence of a hot deconfined medium may also affect heavyquark hadronization, being possible for them to recombine with the surrounding light thermal partons, so that the final heavy-flavour hadrons inherit part of the flow of the medium. Here we show how it is possible to develop a complete transport setup allowing one to describe heavy-flavour production in high-energy nuclear collisions, displaying some major results one can obtain. Finally, the possibility that the formation of a hot deconfined medium even in small systems (high-multiplicity p-Au and d-Au collisions, so far) may affect also heavy-flavour observables is investigated.

  13. Medium effects on heavy-flavour observables in high-energy nuclear collisions

    Directory of Open Access Journals (Sweden)

    Beraudo Andrea

    2016-01-01

    Full Text Available The peculiar role of heavy-flavour observables in relativistic heavy-ion collisions is discussed. Produced in the early stage, c and b quarks cross the hot medium arising from the collision, interacting strongly with the latter, until they hadronize. Depending on the strength of the interaction heavy quarks may or not approach kinetic equilibrium with the plasma, tending in the first case to follow the collective flow of the expanding fireball. The presence of a hot deconfined medium may also affect heavyquark hadronization, being possible for them to recombine with the surrounding light thermal partons, so that the final heavy-flavour hadrons inherit part of the flow of the medium. Here we show how it is possible to develop a complete transport setup allowing one to describe heavy-flavour production in high-energy nuclear collisions, displaying some major results one can obtain. Finally, the possibility that the formation of a hot deconfined medium even in small systems (high-multiplicity p-Au and d-Au collisions, so far may affect also heavy-flavour observables is investigated.

  14. Rapidity and energy dependence of the electric charge correlations in A+A collisions at the SPS energies

    CERN Document Server

    Alt, C; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Gladysz-Dziadus, E; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Lacey, R; Van Leeuwen, M; Lévai, Peter; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Seyboth, P; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strabel, C; Ströbele, H; Susa, T; Szentpétery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wetzler, A; Wlodarczyk, Z; Wojtaszek, A; Yoo, I K; Zimányi, J

    2007-01-01

    Results from electric charge correlations studied with the Balance Function method in A+A collisions from 20\\emph{A} to 158\\emph{A} GeV are presented in two different rapidity intervals: In the mid-rapidity region we observe a decrease of the width of the Balance Function distribution with increasing centrality of the collision, whereas this effect vanishes in the forward rapidity region. Results from the energy dependence study in central Pb+Pb collisions show that the narrowing of the Balance Function expressed by the normalised width parameter \\textit{W} increases with energy towards the highest SPS and RHIC energies. Finally we compare our experimental data points with predictions of several models. The hadronic string models UrQMD and HIJING do not reproduce the observed narrowing of the Balance Function. However, AMPT which contains a quark-parton transport phase before hadronization can reproduce the narrowing of the BF's width with centrality. This confirms the proposed sensitivity of the Balance Func...

  15. Universality, maximum radiation, and absorption in high-energy collisions of black holes with spin.

    Science.gov (United States)

    Sperhake, Ulrich; Berti, Emanuele; Cardoso, Vitor; Pretorius, Frans

    2013-07-26

    We explore the impact of black hole spins on the dynamics of high-energy black hole collisions. We report results from numerical simulations with γ factors up to 2.49 and dimensionless spin parameter χ=+0.85, +0.6, 0, -0.6, -0.85. We find that the scattering threshold becomes independent of spin at large center-of-mass energies, confirming previous conjectures that structure does not matter in ultrarelativistic collisions. It has further been argued that in this limit all of the kinetic energy of the system may be radiated by fine tuning the impact parameter to threshold. On the contrary, we find that only about 60% of the kinetic energy is radiated for γ=2.49. By monitoring apparent horizons before and after scattering events we show that the "missing energy" is absorbed by the individual black holes in the encounter, and moreover the individual black-hole spins change significantly. We support this conclusion with perturbative calculations. An extrapolation of our results to the limit γ→∞ suggests that about half of the center-of-mass energy of the system can be emitted in gravitational radiation, while the rest must be converted into rest-mass and spin energy.

  16. Measurements of low energy observables in proton-proton collisions with the ATLAS Detector.

    CERN Document Server

    Myska, Miroslav; The ATLAS collaboration

    2017-01-01

    Low energy phenomena have been studied in detail at the LHC, providing important input for improving models of non-perturbative QCD effects. The ATLAS collaboration has performed several new measurements in this sector: We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton--proton collisions at a centre-of-mass energy of 13 TeV. The results are corrected for detector effects and compared to predictions from various Monte Carlo generators. ATLAS has also studied the correlated hadron production. In particular, an analysis of the momentum difference between charged hadrons in high–energy proton–proton collisions is performed and the results are compared to the predictions of a helical QCD string fragmentation model. New results in forward physics are expected to be available soon. We close this presentation with the measurement of the exclusive "\\gamma\\gamma \\rightarrow \\mu^{+}\\mu^{-}" production in proton-proton collisions at a center-of-mass ...

  17. Lead-ion collisions: the LHC achieves a new energy record

    CERN Multimedia

    John Jowett

    2015-01-01

    After the Bevatron (Berkeley, 1954) – which broke the energy barrier of billions of electronvolts – and the Tevatron (Fermilab, 1987) – which reached a trillion electronvolts – the LHC is now reaching the peta- (quadrillion) electronvolt level with its heavy-ion collisions (see here). However, one should remember that the average energy per colliding nucleon pair, within the 1 PeV “fireball”, is 5 TeV (compared to 13 TeV in the recent proton-proton collisions).   Heavy-ion collision events from the ALICE, ATLAS, CMS and LHCb experiments. Two of the great particle accelerators of the past were named after the symbolic energy barrier that they broke. The Bevatron (for "billions of electronvolts synchrotron"), at Berkeley in 1954, was the first to break the barrier of a billion electronvolts or BeV (now known as a gigaelectronvolt or GeV) in the centre-of-mass, by a large enough margin to create the laboratory’s ...

  18. Academic Training - Tevatron: studying pp collisions at the highest energy

    CERN Multimedia

    2006-01-01

    ACADEMIC TRAINING LECTURE SERIES 15, 16, 17, 18 May Main Auditorium, bldg. 500 on 15, 16, 17 May - Council Chamber on 18 May Physics at the Tevatron B. HEINEMANN, Univ. of Liverpool, FERMILAB Physics Results from the Tevatron The Tevatron proton-antiproton collider at Fermilab in the US is currently the world's highest energy collider. At the experiments CDF and D0 a broad physics programme is being pursued, ranging from flavour physics via electroweak precision measurements to searches for the Higgs boson and new particles beyond the Standard Model. In my lecture I will describe some of the highlight measurements in the flavour, electroweak and searches sectors, and the experimental techniques that are used. ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please tell to your supervisor and apply electronically from the course description pages that can be found on the Web at: http://www.cern.ch/...

  19. (Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions)

    Energy Technology Data Exchange (ETDEWEB)

    Loveland, W.D.

    1991-08-01

    The work described herein is part of a project involving the study of low energy (< 10 MeV/A), intermediate energy (10--100 MeV/A) and relativistic (> 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of best'' semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated.

  20. Dust kinetic Alfvén solitary and rogue waves in a superthermal dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Saini, N. S., E-mail: nssaini@yahoo.com; Singh, Manpreet, E-mail: singhmanpreet185@gmail.com [Department of Physics, Guru Nanak Dev University, Amritsar 143005 (India); Bains, A. S., E-mail: bainsphysics@yahoo.co.in [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2 (Canada)

    2015-11-15

    Dust kinetic Alfvén solitary waves (DKASWs) have been examined in a low-β dusty plasma comprising of negatively charged dust grains, superthermal electrons, and ions. A nonlinear Korteweg-de Vries (KdV) equation has been derived using the reductive perturbation method. The combined effects of superthermality of charged particles (via κ), plasma β, obliqueness of propagation (θ), and dust concentration (via f) on the shape and size of the DKASWs have been examined. Only negative potential (rarefactive) structures are observed. Further, characteristics of dust kinetic Alfvén rogue waves (DKARWs), by deriving the non-linear Schrödinger equation (NLSE) from the KdV equation, are studied. Rational solutions of NLSE show that rogue wave envelopes are supported by this plasma model. It is observed that the influence of various plasma parameters (superthermality, plasma β, obliqueness, and dust concentration) on the characteristics of the DKARWs is very significant. This fundamental study may be helpful in understanding the formation of coherent nonlinear structures in space and astrophysical plasma environments where superthermal particles are present.

  1. Kinetic Alfvén solitary and rogue waves in superthermal plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Bains, A. S.; Li, Bo, E-mail: bbl@sdu.edu.cn; Xia, Li-Dong [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai (China)

    2014-03-15

    We investigate the small but finite amplitude solitary Kinetic Alfvén waves (KAWs) in low β plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter κ, plasma β, and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfvénic, compressive solitons are supported. We then extend the study to examine kinetic Alfvén rogue waves by deriving a nonlinear Schrödinger equation from the KdV equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermality whereas the opposite is true when the plasma β increases. The findings of this study may find applications to low β plasmas in astrophysical environments where particles are superthermally distributed.

  2. Differential and total cross sections of mutual neutralization in low-energy collisions of isotopes of H++H-

    Science.gov (United States)

    Nkambule, Sifiso M.; Elander, Nils; Larson, Åsa; Lecointre, Julien; Urbain, Xavier

    2016-03-01

    Mutual neutralization in the collisions of H+ and H- is studied both theoretically and experimentally. The quantum-mechanical ab initio model includes covalent states associated with the H (1 )+H (n ≤3 ) limits and the collision energy ranges from 1 meV to 100 eV. The reaction is theoretically studied for collisions between different isotopes of the hydrogen ions. From the partial wave scattering amplitude, the differential and total cross sections are computed. The differential cross section is analyzed in terms of forward- and backward-scattering events, showing a dominance of backward scattering which can be understood by examining the phase of the scattering amplitudes for the gerade and ungerade set of states. The isotope dependence of the total cross section is compared with the one obtained using a semiclassical multistate Landau-Zener model. The final state distribution analysis emphasizes the dominance of the n =3 channel for collisions below 10 eV, while at higher collision energies, the n =2 channel starts to become important. For collisions of ions forming a molecular system with a larger reduced mass, the n =2 channel starts to dominate at lower energies. Using a merged ion-beam apparatus, the branching ratios for mutual neutralization in H+ and H- collisions in the energy range from 11 to 185 eV are measured with position- and time-sensitive particle detectors. The measured and calculated branching ratios satisfactorily agree with respect to state contributions.

  3. Signals of new physics in global event properties in pp collisions in the TeV energy domain: rapidity intervals

    CERN Document Server

    Giovannini, Alberto

    2003-01-01

    The study of possible new physics signals in global event properties in pp collisions in the TeV energy domain is extended from full phase-space to rapidity intervals experimentally accessible at LHC. The elbow structure in the total multiplicity distribution predicted in full phase-space is clearly present also in restricted rapidity intervals, leading to very strong charged particle correlations. It is also found that energy densities comparable to those reached in heavy ion collisions at RHIC could be attained in pp collisions at LHC.

  4. Study of $b\\bar{b}$ correlations in high energy proton-proton collisions

    CERN Document Server

    Aaij, Roel; LHCb Collaboration; Adinolfi, Marco; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Alfonso Albero, Alejandro; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Andreassi, Guido; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Archilli, Flavio; d'Argent, Philippe; Arnau Romeu, Joan; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Babuschkin, Igor; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baker, Sophie; Balagura, Vladislav; Baldini, Wander; Baranov, Alexander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Baryshnikov, Fedor; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Beiter, Andrew; Bel, Lennaert; Beliy, Nikita; Bellee, Violaine; Belloli, Nicoletta; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Beranek, Sarah; Berezhnoy, Alexander; Bernet, Roland; Berninghoff, Daniel; Bertholet, Emilie; Bertolin, Alessandro; Betancourt, Christopher; Betti, Federico; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bezshyiko, Iaroslava; Bifani, Simone; Billoir, Pierre; Birnkraut, Alex; Bitadze, Alexander; Bizzeti, Andrea; Bjørn, Mikkel; Blake, Thomas; Blanc, Frederic; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Boettcher, Thomas; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Bordyuzhin, Igor; Borgheresi, Alessio; Borghi, Silvia; Borisyak, Maxim; Borsato, Martino; Bossu, Francesco; Boubdir, Meriem; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Braun, Svende; Britton, Thomas; Brodzicka, Jolanta; Brundu, Davide; Buchanan, Emma; Burr, Christopher; Bursche, Albert; Buytaert, Jan; Byczynski, Wiktor; Cadeddu, Sandro; Cai, Hao; Calabrese, Roberto; Calladine, Ryan; Calvi, Marta; Calvo Gomez, Miriam; Camboni, Alessandro; Campana, Pierluigi; Campora Perez, Daniel Hugo; Capriotti, Lorenzo; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carniti, Paolo; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cavallero, Giovanni; Cenci, Riccardo; Chamont, David; Charles, Matthew; Charpentier, Philippe; Chatzikonstantinidis, Georgios; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu Faye; Chitic, Stefan-Gabriel; Chobanova, Veronika; Chrzaszcz, Marcin; Chubykin, Alexsei; Ciambrone, Paolo; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Cogan, Julien; Cogneras, Eric; Cogoni, Violetta; Cojocariu, Lucian; Collins, Paula; Colombo, Tommaso; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombs, George; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Costa Sobral, Cayo Mar; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Crocombe, Andrew; Cruz Torres, Melissa Maria; Currie, Robert; D'Ambrosio, Carmelo; Da Cunha Marinho, Franciole; Dall'Occo, Elena; Dalseno, Jeremy; Davis, Adam; De Aguiar Francisco, Oscar; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Serio, Marilisa; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Del Buono, Luigi; Dembinski, Hans Peter; Demmer, Moritz; Dendek, Adam; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Dey, Biplab; Di Canto, Angelo; Di Nezza, Pasquale; Dijkstra, Hans; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Douglas, Lauren; Dovbnya, Anatoliy; Dreimanis, Karlis; Dufour, Laurent; Dujany, Giulio; Durante, Paolo; Dzhelyadin, Rustem; Dziewiecki, Michal; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Ebert, Marcus; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Farley, Nathanael; Farry, Stephen; Fay, Robert; Fazzini, Davide; Federici, Luca; Ferguson, Dianne; Fernandez, Gerard; Fernandez Declara, Placido; Fernandez Prieto, Antonio; Ferrari, Fabio; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fini, Rosa Anna; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fleuret, Frederic; Fohl, Klaus; Fontana, Marianna; Fontanelli, Flavio; Forshaw, Dean Charles; Forty, Roger; Franco Lima, Vinicius; Frank, Markus; Frei, Christoph; Fu, Jinlin; Funk, Wolfgang; Furfaro, Emiliano

    2017-01-01

    Kinematic correlations for pairs of beauty hadrons, produced in high energy proton-proton collisions, are studied. The data sample used was collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV and corresponds to an integrated luminosity of 3 fb$^{-1}$ The measurement is performed using inclusive $b\\rightarrow J/\\psi X$ decays in the rapidity range $2 < y^{J/\\psi} <4.5$. The observed correlations are in good agreement with theoretical predictions.

  5. Jet tomography of high-energy nucleus-nucleus collisions at next-to-leading order

    Energy Technology Data Exchange (ETDEWEB)

    Vitev, Ivan [Los Alamos National Laboratory; Zhang, Ben - Wei [Los Alamos National Laboratory

    2009-01-01

    We demonstrate that jet observables are highly sensitive to the characteristics of the vacuum and the in-medium QCD parton showers and propose techniques that exploit this sensitivity to constrain the mechanism of quark and gluon energy loss in strongly-interacting plasmas. As a first example, we calculate the inclusive jet cross section in high-energy nucleus-nucleus collisions to {Omicron}({alpha}{sub s}{sup 3}). Theoretical predictions for the medium-induced jet broadening and the suppression of the jet production rate due to cold and hot nuclear matter effects in Au+Au and Cu+Cu reactions at RHIC are presented.

  6. Nuclear Stopping in Central Au+Au Collisions at RHIC Energies

    Directory of Open Access Journals (Sweden)

    Ying Yuan

    2014-01-01

    Full Text Available Nuclear stopping in central Au+Au collisions at relativistic heavy-ion collider (RHIC energies is studied in the framework of a cascade mode and the modified ultrarelativistic quantum molecular dynamics (UrQMD transport model. In the modified mode, the mean field potentials of both formed and “preformed” hadrons (from string fragmentation are considered. It is found that the nuclear stopping is increasingly influenced by the mean-field potentials in the projectile and target regions with the increase of the reaction energy. In the central region, the calculations of the cascade model considering the modifying factor can describe the experimental data of the PHOBOS collaboration.

  7. Nuclear symmetry energy in calcium-calcium collisions (INDRA-VAMOS

    Directory of Open Access Journals (Sweden)

    Chartier M.

    2012-07-01

    Full Text Available The density dependence of the symmetry energy is of great interest to many fields of nuclear physics and nuclear astro-physics. The E503 INDRA-VAMOS experiment performed at GANIL in 2007 is intended to provide further sub-saturation constraints using calcium-calcium collisions around the Fermi energy (35AMeV. In these proceedings this experiment will be discussed in the context of the physics it is aiming to study and will give a brief summary of the current progress of the data analysis.

  8. A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks

    OpenAIRE

    Kilhung Lee

    2010-01-01

    This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is eit...

  9. Inclusive Glueball Production in High-Energy p+p(p-) Collisions

    Institute of Scientific and Technical Information of China (English)

    彭宏安; 段春贵; 何祯民

    2001-01-01

    Using the factorizable character of amplitudes for the double diffractive process in the Landshoff-Nachtmann model, we have discussed the inclusive glueball production in high-energy pp collisions via the fusion process of two non-perturbative gluons, and have compared it with the double diffractive alike process. We found that, as the c.m. energy Ecms increases from 20 to 20 000 GeV, the cross sections of the latter process are about one to two orders larger than the former. Such an outcome could be explained from the hypothesis of duality between glueballs and pomeron.

  10. Quantum dynamics of rovibrational transitions in H2-H2 collisions: internal energy and rotational angular momentum conservation effects.

    Science.gov (United States)

    Fonseca dos Santos, S; Balakrishnan, N; Lepp, S; Quéméner, G; Forrey, R C; Hinde, R J; Stancil, P C

    2011-06-01

    We present a full dimensional quantum mechanical treatment of collisions between two H(2) molecules over a wide range of energies. Elastic and state-to-state inelastic cross sections for ortho-H(2) + para-H(2) and ortho-H(2) + ortho-H(2) collisions have been computed for different initial rovibrational levels of the molecules. For rovibrationally excited molecules, it has been found that state-to-state transitions are highly specific. Inelastic collisions that conserve the total rotational angular momentum of the diatoms and that involve small changes in the internal energy are found to be highly efficient. The effectiveness of these quasiresonant processes increases with decreasing collision energy and they become highly state-selective at ultracold temperatures. They are found to be more dominant for rotational energy exchange than for vibrational transitions. For non-reactive collisions between ortho- and para-H(2) molecules for which rotational energy exchange is forbidden, the quasiresonant mechanism involves a purely vibrational energy transfer albeit with less efficiency. When inelastic collisions are dominated by a quasiresonant transition calculations using a reduced basis set involving only the quasiresonant channels yield nearly identical results as the full basis set calculation leading to dramatic savings in computational cost.

  11. Collective Flow in Heavy Ion Collisions at Low to Relativistic Energies

    Science.gov (United States)

    Lisa, M. A.

    1997-04-01

    Recently, the phenomenon of collective flow in heavy ion collisions has been the subject of intense study. First observed at the Bevalac more than a decade ago, flow is now recognized as a universal feature of heavy ion collisions at all bombarding energies. Recent developments in three identified forms of flow-- sidewards flow, radial flow, and squeeze-out-- will be reviewed. At low energies (EOS and FOPI collaborations have considerably extended the work begun by the Plastic Ball group; here, studies of the flow of nucleons, fragments, and pions lead to a better understanding of the Equation of State of nuclear matter, momentum dependent interactions, and pion shadowing. The squeeze-out effect at Bevalac energies may be the most sensitive form of flow to the equation of state. Recent studies suggest that squeeze-out may be considered as an azimuthal modulation of the radial flow. The E895 collaboration is continuing the flow excitation function of the EOS/FOPI groups for 2-10 A GeV bombarding energies, with the aim of increasing the sensitivity to Equation of State parameters, as well as searching for flow signatures of Quark Gluon Plasma creation. Sidewards flow at the highest AGS energy for Au beams(11 A GeV) has been reported by the E877 collaboration, which has correlated the effect with pion interferometry measurements to identify possible dynamical correlations in the collision. Finally, at the highest energies currently available, the NA49 collaboration has found sidewards flow at SPS energies (160 A GeV); preliminary comparisons to RQMD calculations indicate that the model reproduces the flow well. At all of these bombarding energies (over 3 orders of magnitude!), the particle spectra show a strong non-thermal component which has been identified as largely isotropic or "radial" flow. While the sidewards flow accounts for only ~5% of emitted particles' energy, roughly 30-50% of the energy of emitted particles is found in radial flow. Several groups are

  12. Vibrational and Electronic Energy Transfer and Dissociation of Diatomic Molecules by Electron Collisions

    Science.gov (United States)

    Huo, Winifred M.; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    At high altitudes and velocities equal to or greater than the geosynchronous return velocity (10 kilometers per second), the shock layer of a hypersonic flight will be in thermochemical nonequilibrium and partially ionized. The amount of ionization is determined by the velocity. For a trans atmospheric flight of 10 kilometers per second and at an altitude of 80 kilometers, a maximum of 1% ionization is expected. At a velocity of 12 - 17 kilometer per second, such as a Mars return mission, up to 30% of the atoms and molecules in the flow field will be ionized. Under those circumstances, electrons play an important role in determining the internal states of atoms and molecules in the flow field and hence the amount of radiative heat load and the distance it takes for the flow field to re-establish equilibrium. Electron collisions provide an effective means of transferring energy even when the electron number density is as low as 1%. Because the mass of an electron is 12,760 times smaller than the reduced mass of N2, its average speed, and hence its average collision frequency, is more than 100 times larger. Even in the slightly ionized regime with only 1% electrons, the frequency of electron-molecule collisions is equal to or larger than that of molecule-molecule collisions, an important consideration in the low density part of the atmosphere. Three electron-molecule collision processes relevant to hypersonic flows will be considered: (1) vibrational excitation/de-excitation of a diatomic molecule by electron impact, (2) electronic excitation/de-excitation, and (3) dissociative recombination in electron-diatomic ion collisions. A review of available data, both theory and experiment, will be given. Particular attention will be paid to tailoring the molecular physics to the condition of hypersonic flows. For example, the high rotational temperatures in a hypersonic flow field means that most experimental data carried out under room temperatures are not applicable. Also

  13. Heavy quark pair production in high energy pA collisions: Open heavy flavors

    CERN Document Server

    Fujii, Hirotsugu

    2013-01-01

    We study open heavy flavor meson production in proton-nucleus (pA) collisions at RHIC and LHC energies within the Color Glass Condensate framework. We use the unintegrated gluon distribution at small Bjorken's x in the proton obtained by solving the Balitsky-Kovchegov equation with running coupling correction and constrained by global fitting of HERA data. We change the initial saturation scale of the gluon distribution for the heavy nucleus. The gluon distribution with McLerran-Venugopalan model initial condition is also used for comparison. We present transverse momentum spectra of single D and B productions in pA collisions, and the so-called nuclear modification factor. The azimuthal angle correlation of open heavy flavor meson pair is also computed to study the modification due to the gluon saturation in the heavy nucleus at the LHC.

  14. Probing the nuclear equation-of-state and the symmetry energy with heavy-ion collisions

    Directory of Open Access Journals (Sweden)

    Verde Giuseppe

    2014-03-01

    Full Text Available The present status of studies aimed at constraining the nuclear equation of state with heavy-ion collision dynamics is presented. Multifragmentation phenomena, including their isotopic distributions, charge correlations and emission time-scales, may revel the existence of liquid-gas transitions in the phase diagram. Exploring the isotopic degree of freedom in nuclear dynamics is then required in order to constrain the equation of state of asymmetric nuclear matter which presently represents a major priority due to its relevance to both nuclear physics and astrophysics. Some observables that have successfully constrained the density dependence of the symmetry energy are presented, such as neutron-proton yield ratios and isospin diffusion and drift phenomena. The reported results and status of the art is discussed by also considering some of the present problems and some future perspectives for the heavy-ion collision community.

  15. An Apparatus for the Measurement of Various Scattering Processes in Intermediate Energy, Ion - Atom Collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kvale, T. J.; Seely, D. G.

    1998-07-01

    This paper summarizes the main features of an apparatus constructed at the University of Toledo for the study of various scattering processes in intermediate energy, ion - atom collisions. The main purpose of this facility is to provide experimental data which serve as benchmarks to test current scattering theories for those processes. Recent measurements of single electron detachment (SED) and double electron detachment (DED) total cross sections for 5-50 keV H{sup -} ions incident on noble gases and for 10-50 keV H{sup -} ions incident on CH{sub 4} molecules were conducted in this laboratory. As a result of an analysis of the scattered beam growth curves, information about other charge-changing cross sections in the hydrogen-atom (molecule) collision systems were obtain, as well.

  16. Diffractive charmonium spectrum in high energy collisions in the basis light-front quantization approach

    CERN Document Server

    Chen, Guangyao; Maris, Pieter; Tuchin, Kirill; Vary, James P

    2016-01-01

    Using the charmonium light-front wavefunctions obtained by diagonalizing an effective Hamiltonian with the one-gluon exchange interaction and a confining potential inspired by light-front holography in the basis light-front quantization formalism, we compute production of charmonium states in diffractive deep inelastic scattering and ultra-peripheral heavy ion collisions within the dipole picture. Our method allows us to predict yields of all excited charmonium and bottomonium states below the open flavor thresholds in high-energy deep inelastic scattering, proton-nucleus and ultra-peripheral heavy ion collisions. The obtained charmonium cross section is in reasonable agreement with experimental data at HERA, RHIC and LHC. We observe that the cross-section ratio $\\sigma_{\\Psi(2s)}/\\sigma_{J/\\Psi}$ reveals significant independence of model parameters.

  17. Fluctuations of the initial color fields in high energy heavy ion collisions

    CERN Document Server

    Epelbaum, Thomas

    2013-01-01

    In the Color Glass Condensate approach to the description of high energy heavy ion collisions, one needs to superimpose small random Gaussian distributed fluctuations to the classical background field, in order to resum the leading secular terms that result from the Weibel instability, that would otherwise lead to pathological results beyond leading order. In practical numerical simulations, one needs to know this spectrum of fluctuations at a proper time $\\tau \\ll Q_s^{-1}$ shortly after the collision, in the Fock-Schwinger gauge $\\ma{A}^\\tau=0$. In this paper, we derive these fluctuations from first principles, by solving the Yang-Mills equations linearized around the classical background, with plane wave initial conditions in the remote past. We perform the intermediate steps in light-cone gauge, and we convert the results to the Fock-Schwinger gauge at the end. We obtain simple and explicit formulas for the fluctuation modes.

  18. Fluid simulation of dispersive and nondispersive ion acoustic waves in the presence of superthermal electrons

    Science.gov (United States)

    Lotekar, Ajay; Kakad, Amar; Kakad, Bharati

    2016-10-01

    One-dimensional fluid simulation is performed for the unmagnetized plasma consisting of cold fluid ions and superthermal electrons. Such a plasma system supports the generation of ion acoustic (IA) waves. A standard Gaussian type perturbation is used in both electron and ion equilibrium densities to excite the IA waves. The evolutionary profiles of the IA waves are obtained by varying the superthermal index and the amplitude of the initial perturbation. This simulation demonstrates that the amplitude of the initial perturbation and the superthermal index play an important role in determining the time evolution and the characteristics of the generated IA waves. The initial density perturbation in the system creates charge separation that drives the finite electrostatic potential in the system. This electrostatic potential later evolves into the dispersive and nondispersive IA waves in the simulation system. The density perturbation with the amplitude smaller than 10% of the equilibrium plasma density evolves into the dispersive IA waves, whereas larger density perturbations evolve into both dispersive and nondispersive IA waves for lower and higher superthermal index. The dispersive IA waves are the IA oscillations that propagate with constant ion plasma frequency, whereas the nondispersive IA waves are the IA solitary pulses (termed as IA solitons in the stability region) that propagate with the constant wave speed. The characteristics of the stable nondispersive IA solitons are found to be consistent with the nonlinear fluid theory. To the best of our knowledge, this is the first fluid simulation study that has considered the superthermal distributions for the plasma species to model the electrostatic solitary waves.

  19. Absorbed Dose and Collision Kerma Relationship for High-Energy Photons

    Science.gov (United States)

    Sibata, Claudio Hissao

    Historically, exposure has been used as an important quantity to specify X- or (gamma)- ray beams. For any photon beam the energy fluence is proportional to the exposure. Exposure can be calculated and/or measured if the spectrum of the beam is known and charged particle equilibrium (CPE) exists. For low energy photons (up to approximately 1 MeV), due to the existence of CPE, absorbed dose (D) is equal to the collision kerma (K(,c)). For megavoltage photons this equality is lost due to CPE failure, which also restricts the measurement of exposure. It is possible, though, to find a relationship between the absorbed dose and collision kerma when transient charged particle equilibrium (TCPE) exists. This basic idea was originally proposed by Roesch in 1958 and its refinement has been discussed by Attix in 1979 and 1983. The modified Roesch's formula which enables us to measure exposure even for high-energy photons is given by D = (beta) K(,c) (TURNEQ) K(,c) (1 + (mu)' ) where (mu)' is the effective linear attenuation coefficient and is the mean distance the secondary electrons carry kinetic energy in the direction of the photon beam while depositing it as absorbed dose. The symbol (beta) is the quotient of the absorbed dose and the collision kerma. The importance of Roesch's formula has been recognized and used implicitly in the recent dosimetry protocol of the AAPM (Task Group 21). However, the value used in the protocol is based on theoretical calculations which do not include photon scattering. As a result of the present effort the parameters (mu)' and have been determined experimentally, for the first time. The dependence of (beta) on several factors has been studied and (beta) has been obtained including the effects of scattering. Calculations were also performed for several photon energies and materials, using the Roesch method, which does not include photon scattering effects. Comparisons of measured and calculated values of show reasonable agreement.

  20. Collisions of low-energy antiprotons and protons with atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Luehr, Armin

    2010-02-18

    Antiproton (anti p) collisions have evolved to a powerful tool for the testing of dynamic electron correlations in atoms and molecules. While advances in the understanding of anti p collisions with the simplest one- and two-electron atoms, H and He, have been achieved experiment and theory did not agree for low-energy anti p+He collisions (<40 keV), stimulating a vivid theoretical activity. On the other hand, only very few theoretical anti p studies can be found considering molecular as well as other atomic targets, in contrast to proton (p) collisions. This is in particular true for anti p impacts on H{sub 2} despite its fundamental role in representing the simplest two-electron molecule. The obtained results may be useful for the anti p experiments at CERN (e.g., antihydrogen production) and in particular for the facility design of low-energy anti p storage rings (e.g., at FLAIR) where a precise knowledge of the anti p interaction with the dominant residual-gas molecule H{sub 2} is needed. In this work a nonperturbative, time-dependent numerical approach is developed which describes ionization and excitation of atoms or molecules by either anti p or p impact based on the impact-parameter method. A spectral close-coupling method is employed for solving the time-dependent Schroedinger equation in which the scattering wave function is expanded in (effective) one- or two-electron eigenstates of the target. This includes for the first time a full two-electron, two-center description of the H{sub 2} molecule in anti p collisions. The radial part of the one-electron eigenstates is expanded in B splines while the two-electron basis is obtained with a configurationinteraction approach. Calculations are performed for anti p collisions with H, H{sub 2}{sup +}, and H{sub 2} as well as with He and alkali-metal atoms Li, Na, K, and Rb. Additionally, data are obtained for p collisions with H{sub 2}, Li, Na, and K. The developed method is tested and validated by detailed

  1. A comprehensive analysis of small-passerine fatalities from collision with turbines at wind energy facilities.

    Science.gov (United States)

    Erickson, Wallace P; Wolfe, Melissa M; Bay, Kimberly J; Johnson, Douglas H; Gehring, Joelle L

    2014-01-01

    Small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the United States (US) and Canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. We used data compiled from 116 studies conducted in the US and Canada to estimate the annual rate of small-bird fatalities. It was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. The remaining 70% of studies provided data on small-bird fatalities. We then adjusted estimates to account for detection bias and loss of carcasses from scavenging. These studies represented about 15% of current operating capacity (megawatts [MW]) for all wind energy facilities in the US and Canada and provided information on 4,975 bird fatalities, of which we estimated 62.5% were small passerines comprising 156 species. For all wind energy facilities currently in operation, we estimated that about 134,000 to 230,000 small-passerine fatalities from collision with wind turbines occur annually, or 2.10 to 3.35 small birds/MW of installed capacity. When adjusted for species composition, this indicates that about 368,000 fatalities for all bird species are caused annually by collisions with wind turbines. Other human-related sources of bird deaths, (e.g., communication towers, buildings [including windows]), and domestic cats) have been estimated to kill millions to billions of birds each year. Compared to continent-wide population estimates, the cumulative mortality rate per year by species was highest for black-throated blue warbler and tree swallow; 0.043% of the entire population of each species was estimated to annually suffer mortality from collisions with turbines. For the eighteen species with the next highest values, this estimate ranged from 0.008% to 0.038%, much lower than rates attributed to collisions with communication towers (1.2% to 9.0% for top twenty species).

  2. A comprehensive analysis of small-passerine fatalities from collisions with turbines at wind energy facilities

    Science.gov (United States)

    Erickson, Wallace P.; Wolfe, Melissa M.; Bay, Kimberly J.; Johnson, Douglas H.; Gehring, Joelle L.

    2014-01-01

    Small passerines, sometimes referred to as perching birds or songbirds, are the most abundant bird group in the United States (US) and Canada, and the most common among bird fatalities caused by collision with turbines at wind energy facilities. We used data compiled from 39 studies conducted in the US and Canada to estimate the annual rate of small-bird fatalities. It was necessary for us to calculate estimates of small-bird fatality rates from reported all-bird rates for 30% of studies. The remaining 70% of studies provided data on small-bird fatalities. We then adjusted estimates to account for detection bias and loss of carcasses from scavenging. These studies represented about 15% of current operating capacity (megawatts [MW]) for all wind energy facilities in the US and Canada and provided information on 4,975 bird fatalities, of which we estimated 62.5% were small passerines comprising 156 species. For all wind energy facilities currently in operation, we estimated that about 134,000 to 230,000 small-passerine fatalities from collision with wind turbines occur annually, or 2.10 to 3.35 small birds/MW of installed capacity. When adjusted for species composition, this indicates that about 368,000 fatalities for all bird species are caused annually by collisions with wind turbines. Other human-related sources of bird deaths, (e.g., communication towers, buildings [including windows]), and domestic cats) have been estimated to kill millions to billions of birds each year. Compared to continent-wide population estimates, the cumulative mortality rate per year by species was highest for black-throated blue warbler and tree swallow; 0.043% of the entire population of each species was estimated to annually suffer mortality from collisions with turbines. For the eighteen species with the next highest values, this estimate ranged from 0.008% to 0.038%, much lower than rates attributed to collisions with communication towers (1.2% to 9.0% for top twenty species).

  3. Energy dependence of non-linear dynamical features in e+e- collisions

    Institute of Scientific and Technical Information of China (English)

    LI Di-Kai; CHEN Gang; WEI Hui-Ling

    2008-01-01

    A study of the dynamical fluctuation properties at various c.m. Energies in e+e- collisions is performed using the Monte Carlo method. The results suggest that, after the normalized factorial moments of 3-dimensional phase space are analyzed using an isotropical phase space partition, the NFM describing non-linear dynamical properties show a power-law scaling, I.e., the dynamical fluctuations in higher dimensional phase space are isotropic. For c.m. Energies √s≤80 GeV,the scaling exponents φq increase rapidly with the c.m. Energy and for c.m. Energies √s>80 GeV,the φq gradually saturate.

  4. Jet Energy Calibrations at the CMS experiment with 13 TeV collisions

    CERN Document Server

    Stoever, Marc

    2017-01-01

    The jet energy calibration (JEC) measurements, based on a data sample collected in proton-proton collisions at a center-of-mass energy of 13~TeV recorded by the CMS experiment at the LHC Run 2 are presented. The calibrations are extracted from data and simulated events and employ the combination of several channels and methods. These successively correct for contributions of pileup, and absolute scale of the jet energy scale as a function of $\\eta$ and $p_{\\rm{T}}$ in simulation. To account for any residual differences with jet energy scale in data, in-situ calibrations are determined using dijet, photon+jets, Z+jets and multijet events. Several techniques are used to account for various sources of scale corrections and their uncertainties.

  5. (1 + 1) dimensional hydrodynamics for high-energy heavy-ion collisions

    Science.gov (United States)

    Satarov, L. M.; Mishustin, I. N.; Merdeev, A. V.; Stöcker, H.

    2007-10-01

    A (1 + 1)-dimensional hydrodynamical model in the light-cone coordinates is used to describe central heavy-ion collisions at ultrarelativistic bombarding energies. Deviations from Bjorken scaling are taken into account by choosing finite-size profiles for the initial energy density. The sensitivity of fluid-dynamical evolution to the equation of state and the parameters of initial state are investigated. Experimental constraints on the total energy of produced particles are used to reduce the number of model parameters. Spectra of secondary particles are calculated under the assumption that the transition from the hydrodynamical stage to the collisionless expansion of matter occurs at a certain freeze-out temperature. An important role of resonances in the formation of observed hadronic spectra is demonstrated. The calculated rapidity distributions of pions, kaons, and antiprotons in central Au + Au collisions at √s NN = 200 GeV are compared with experimental data of the BRAHMS Collaboration. Parameters of the initial state are reconstructed for different choices of the equation of state. The best fit of these data is obtained for a soft equation of state and Gaussian-like initial profiles of the energy density, intermediate between the Landau and Bjorken limits.

  6. Inclusive photon production at forward rapidities in pp collisions at LHC energies with the ALICE experiment

    Science.gov (United States)

    Sudipan Dethe ALICE Collaboration

    2016-04-01

    Measurements of multiplicity and pseudorapidity distributions of particles produced in pp collisions are important for the study of particle production mechanisms and to obtain baseline distributions to be compared with those from heavy-ion collisions. The inclusive photon measurements (dominated by π0 decays) are complementary to the charged particle measurements. The present work focuses on the forward rapidity region with comparisons to different models such as PYTHIA and PHOJET. We report the measurements of multiplicity and pseudorapidity distributions of inclusive photons using the ALICE Photon Multiplicity Detector (PMD) at forward rapidities (2.3 distributions are well described by negative binomial distributions (NBD). Multiplicity distributions are studied in terms of KNO variables for each energy. It is shown that the increase in the average photon multiplicity as a function of beam energy is compatible with both a logarithmic and power law dependence. The results are compared to different model predictions. These models reproduce experimental results at lower energy while they are not accurate at higher energies.

  7. Charm production in Pb+Pb collisions at the Large Hadron Collider energy

    CERN Document Server

    Song, Taesoo; Cabrera, Daniel; Cassing, Wolfgang; Bratkovskaya, Elena

    2015-01-01

    We study charm production in Pb+Pb collisions at $\\sqrt{s_{\\rm NN}}=$2.76 TeV in the Parton-Hadron-String-Dynamics transport approach and the charm dynamics in the partonic and hadronic medium. The charm quarks are produced through initial binary nucleon-nucleon collisions by using the PYTHIA event generator taking into account the (anti-)shadowing incorporated in the EPS09 package. The produced charm quarks interact with off-shell massive partons in the quark-gluon plasma and are hadronized into $D$ mesons through coalescence or fragmentation close to the critical energy density, and then interact with hadrons in the final hadronic stage with scattering cross sections calculated in an effective Lagrangian approach with heavy-quark spin symmetry. The PHSD results show a reasonable $R_{\\rm AA}$ and elliptic flow of $D$ mesons in comparison to the experimental data for Pb+Pb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV from the ALICE Collaboration. We also study the effect of temperature-dependent off-shell charm q...

  8. Low-energy collisions of helium clusters with size-selected cobalt cluster ions

    Science.gov (United States)

    Odaka, Hideho; Ichihashi, Masahiko

    2017-04-01

    Collisions of helium clusters with size-selected cobalt cluster ions, Com+ (m ≤ 5), were studied experimentally by using a merging beam technique. The product ions, Com+Hen (cluster complexes), were mass-analyzed, and this result indicates that more than 20 helium atoms can be attached onto Com+ at the relative velocities of 103 m/s. The measured size distributions of the cluster complexes indicate that there are relatively stable complexes: Co2+Hen (n = 2, 4, 6, and 12), Co3+Hen (n = 3, 6), Co4+He4, and Co5+Hen (n = 3, 6, 8, and 10). These stabilities are explained in terms of their geometric structures. The yields of the cluster complexes were also measured as a function of the relative velocity (1 × 102-4 × 103 m/s), and this result demonstrates that the main interaction in the collision process changes with the increase of the collision energy from the electrostatic interaction, which includes the induced deformation of HeN, to the hard-sphere interaction. Supplementary material in the form of one pdf file available from the Journal web page at http://https://doi.org/10.1140/epjd/e2017-80015-0

  9. Forward-backward multiplicity fluctuation and longitudinal harmonics in high-energy nuclear collisions

    Science.gov (United States)

    Jia, Jiangyong; Radhakrishnan, Sooraj; Zhou, Mingliang

    2016-04-01

    An analysis method is proposed to study the forward-backward (FB) multiplicity fluctuation in high-energy nuclear collisions, built on the earlier work of Bzdak and Teaney [Phys. Rev. C 87, 024906 (2013), 10.1103/PhysRevC.87.024906]. The method allows the decomposition of the centrality dependence of average multiplicity from the dynamical event-by-event (EbyE) fluctuation of multiplicity in pseudorapidity. Application of the method to AMPT (A Multi-Phase Transport model) and HIJING (Heavy Ion Jet INteraction Generator) models shows that the long-range component of the FB correlation is captured by a few longitudinal harmonics, with the first component driven by the asymmetry in the number of participating nucleons in the two colliding nuclei. The higher-order longitudinal harmonics are found to be strongly damped in AMPT compared to HIJING, due to weaker short-range correlations as well as the final-state effects present in the AMPT model. Two-particle pseudorapidity correlation reveals interesting charge-dependent short-range structures that are absent in HIJING model. The proposed method opens an avenue to elucidate the particle production mechanism and early time dynamics in heavy-ion collisions. Future analysis directions and prospects of using the pseudorapidity correlation function to understand the centrality bias in p +p , p +A, and A+A collisions are discussed.

  10. Medium effects on heavy-flavour observables in high-energy nuclear collisions

    CERN Document Server

    Beraudo, Andrea

    2016-01-01

    The peculiar role of heavy-flavour observables in relativistic heavy-ion collisions is discussed. Produced in the early stage, $c$ and $b$ quarks cross the hot medium arising from the collision, interacting strongly with the latter, until they hadronize. Depending on the strength of the interaction heavy quarks may or not approach kinetic equilibrium with the plasma, tending in the first case to follow the collective flow of the expanding fireball. The presence of a hot deconfined medium may also affect heavy-quark hadronization, being possible for them to recombine with the surrounding light thermal partons, so that the final heavy-flavour hadrons inherit part of the flow of the medium. Here we show how it is possible to develop a complete transport setup allowing one to describe heavy-flavour production in high-energy nuclear collisions, displaying some major results one can obtain. Finally, the possibility that the formation of a hot deconfined medium even in small systems (high-multiplicity p-Au and d-Au ...

  11. Transverse Phenomena in Pion Production in Hadronic Collisions at SPS energy

    CERN Document Server

    Chvála, Ondrej

    A comparative study of pion production in hadronic collisio ns at SPS energies focusing on transverse phenomena is presented. Charged pion densities in p+p, p+C, p+Pb and Pb+Pb interactions, obtained at the CERN SPS with the NA49 detecto r setup, are discussed in the forward hemisphere covering ranges in Feynman x F between 0 and 0.4 and in transverse momentum from 0 to 2.1 GeV/c. A detailed description of the da ta analysis, the corrections and centrality determination is given for p+Pb interaction s using a sample of 2 M events. These data are compared to p+p collisions in order to extract those physics quantities which indicate deviations from the elementary reaction specific t o the presence of the nucleus. The evolution of these quantities as a function of centrality is discussed. Their comparison to p+C and Pb+Pb collisions reveals a smooth dependence on the n umber of collisions per participant. In particular, the enhancement of pion yields at high transverse momentum is studied. It is shown to be gove...

  12. A first look at Au + Au collisions at RHIC energies using the PHOBOS detector

    Indian Academy of Sciences (India)

    Birger Back; M D Baker; D S Barton; R R Betts; R Bindel; A Budzanowski; W Busza; A Carroll; J Corbo; M P Decowski; E Garcia; N George; K Gulbrandsen; S Gushue; C Halliwell; J Hamblen; G A Heintzelman; C Henderson; D Hicks; D J Hofman; R Hollis; R Holyńiski; B Holzman; A Iordanova; E Johnson; J L Kane; J Katzy; N Khan; W Kucewicz; P Kulinich; C M Kuo; W T Lin; S Manly; D McLeod; J Michalowski; A C Mignerey; J Mülmenstädt; R Nouicer; A Olszewski; R Pak; I C Park; H Pernegger; M Rafelski; M Rbeiz; C Reed; L P Remsberg; M Reuter; C Roland; G Roland; L Rosenberg; J Sagerer; P Sarin; P Sawicki; W Skulski; S G Steadman; P Steinberg; G S F Stephans; M Stodulski; A Sukhanov; J-L Tang; R Teng; A Trzupek; C Vale; G J van Nieuwenhuizen; R Verdier; B Wadsworth; F L H Wolfs; B Wosiek; K Woźniak; A H Wuosmaa; B Wyslouch

    2003-05-01

    The PHOBOS detector has been used to study Au + Au collisions at $\\sqrt{S_{NN}}=56$, 130, and 200 GeV. Several global observables have been measured and the results are compared with theoretical models. These observables include the charged-particle multiplicity measured as a function of beam energy, pseudo-rapidity, and centrality of the collision. A unique feature of the PHOBOS detector is its almost complete angular coverage such that these quantities can be studied over a pseudo-rapidity interval of ||≤ 5.4. This allows for an almost complete integration of the total charged particle yield, which is found to be about $N^{\\text{tot}}_{\\text{ch}}=4500± 470$ at $\\sqrt{S_{NN}}=130$ GeV and $N^{\\text{tot}}_{\\text{ch}}=5300± 530$ at $\\sqrt{S_{NN}}$ GeV. The ratio of anti-particles to particles emitted in the mid-rapidity region has also been measured using the PHOBOS magnetic spectrometer. Of particular interest is the ratio of anti-protons to protons in the mid-rapidity region, which was found to be $\\overline{p}/p= 0.6± 0.04$(stat) ± 0.06(syst) at $\\sqrt{S_{NN}}=130$ GeV. This high value suggests that an almost baryon-free region has been produced in the collisions.

  13. Quantum chromodynamics at high energy, theory and phenomenology at hadron colliders; Chromodynamique quantique a haute energie, theorie et phenomenologie appliquee aux collisions de hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Marquet, C

    2006-09-15

    When probing small distances inside a hadron, one can resolve its partonic constituents: quarks and gluons that obey the laws of perturbative Quantum Chromodynamics (QCD). This substructure reveals itself in hadronic collisions characterized by a large momentum transfer: in such collisions, a hadron acts like a collection of partons whose interactions can be described in QCD. In a collision at moderate energy, a hadron looks dilute and the partons interact incoherently. As the collision energy increases, the parton density inside the hadron grows. Eventually, at some energy much bigger than the momentum transfer, one enters the saturation regime of QCD: the gluon density has become so large that collective effects are important. We introduce a formalism suitable to study hadronic collisions in the high-energy limit in QCD, and the transition to the saturation regime. In this framework, we derive known results that are needed to present our personal contributions and we compute different cross-sections in the context of hard diffraction and particle production. We study the transition to the saturation regime as given by the Balitsky-Kovchegov equation. In particular we derive properties of its solutions.We apply our results to deep inelastic scattering and show that, in the energy range of the HERA collider, the predictions of high-energy QCD are in good agreement with the data. We also consider jet production in hadronic collisions and discuss the possibility to test saturation at the Large Hadron Collider. (author)

  14. Energy and system size dependence of phi meson production in Cu+Cu and Au+Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2008-10-28

    We study the beam-energy and system-size dependence of {phi} meson production (using the hadronic decay mode {phi} {yields} K{sup +}K{sup -}) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from midrapidity (|y| < 0.5) for 0.4 < p{sub T} < 5 GeV/c. At a given beam energy, the transverse momentum distributions for {phi} mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The {phi} meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions with a different trend compared to strange baryons. The enhancement for {phi} mesons is observed to be higher at {radical}s{sub NN} = 200 GeV compared to 62.4 GeV. These observations for the produced {phi}(s{bar s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.

  15. Study of event-by-event fluctuations in the charged particle ratio in high energy heavy-ion collisions

    CERN Document Server

    Zhou Dai Mei; Liu Zhi Yi; Lu Zhong Dao; Sá Ben-Hao

    2002-01-01

    Using a hadron and string cascade model, JPCIAE, and the corresponding Monte Carlo event generator, the behavior of the charged particle ratio event-by-event fluctuations in subsystem depending on energy, centrality, resonance decay and rapidity interval was investigated for Pb+Pb collisions at SPS and ALICE energies, and for Au+Au collisions at RHIC energies. The model results of charged particle ratio event-by-event fluctuations as a function of the rapidity interval in Pb+Pb collisions at SPS energies were comparable with the preliminary NA49 data. It turned out that the charged particle ratio fluctuation has no strong energy, centrality, resonance decay and rapidity interval dependences. (13 refs).

  16. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC

    CERN Document Server

    Adamczyk, L; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Sánchez, M Calderón de la Barca; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Leyva, A Davila; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; de Souza, R Derradi; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Don, D M M D Madagodagettige; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen,, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-01-01

    Local parity-odd domains are theorized to form inside a Quark-Gluon-Plasma (QGP) which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect (CME). The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this paper, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39 and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy, and tends to vanish by 7.7 GeV. The implications of these results for the CME will be discussed.

  17. Probing Multi-Strange Dibaryon with Proton-Omega Correlation in High-energy Heavy Ion Collisions

    CERN Document Server

    Morita, Kenji; Etminan, Faisal; Hatsuda, Tetsuo

    2016-01-01

    Two-particle intensity correlation between the proton ($p$) and the Omega-baryon ($\\Omega$) in high-energy heavy ion collisions is studied to unravel the possible spin-2 $p\\Omega$ dibaryon recently suggested by lattice QCD simulations. The ratio of correlation functions between small and large collision systems, $C_{\\rm SL}(Q)$, is proposed to be a new measure to extract the strong $p\\Omega$ interaction without much contamination from the Coulomb attraction. Relevance of this quantity to the experimental observables in heavy-ion collisions is also discussed.

  18. Energy And Centrality Dependence Of Mid-rapidity Charged- Particle Multiplicity In Relativistic Heavy-ion Collisions

    CERN Document Server

    Decowski, M P

    2002-01-01

    The properties of quantum chromodynamics (QCD), the modern theory of the strong interaction, can be investigated through the study of relativistic nucleus- nucleus collisions. Recently, the Relativistic Heavy-Ion Collider (RHIC) was completed and started taking data at ten times higher center-of-mass energies than the previous most energetic heavy-ion collisions. This thesis presents some of the first measurements at RHIC from any experiment. The PHOBOS detector is used to measure the charged particle pseudo- rapidity density at mid-rapidity (i.e., in |η| < 1) as a function of collision energy and centrality. The multiplicity is measured by counting short tracks in the silicon spectrometer; the centrality measurement uses two scintillator detectors covering 3 < |η| < 4.5. The charged particle multiplicity at mid-rapidity for the 6% most central collisions is 379 ± 9(stat.) ± 42(syst.), 555 ± 3(stat.) ± 35(syst.) and 661 &plus...

  19. Manifestation of proton structure in ridge-like correlations in high-energy proton-proton collisions

    CERN Document Server

    Kubiczek, Patryk

    2015-01-01

    Recently, the CMS collaboration reported a long range in rapidity, near-side ('ridge-like') angular correlations in high-energy proton-proton collisions, so called ridge effect. This surprising observation suggests the presence of a collective flow that resembles the one believed to produce a similar correlation hydrodynamically in heavy-ion collisions. If the hydrodynamic description is valid then the effect is triggered by the initial spatial anisotropy of the colliding matter. Estimating this anisotropy within different models of the proton internal structure in comparison with measured angular correlations in high-energy proton-proton collision data could in principle discriminate between different proton models. Inspired by recent theoretical developments, we propose several phenomenological models of the proton structure. Subsequently, we calculate the anisotropy coefficients of the dense matter formed in proton-proton collisions within the formalism of the Monte Carlo Glauber model. We find that some p...

  20. Influence of superthermal plasma particles on the Jeans instability in self-gravitating dusty plasmas with dust charge variations

    Energy Technology Data Exchange (ETDEWEB)

    Hakimi Pajouh, H., E-mail: hakimi@alzahra.ac.ir; Afshari, N.

    2016-11-25

    Highlights: • The current of superthermal electrons and ions on the dust surface is calculated. • Increase in the superthermal particles number increases growth rate of instability. • Increase in the superthermal particles number decreases DA waves frequency. • By decreasing κ, the ratio of electric to self-gravitational force is decreased. • Dust charge variations decreases the ratio of electric to self-gravitational force. - Abstract: A theoretical analysis of the dust acoustic waves in the self-gravitating dusty plasmas is presented within the consideration of the superthermal electrons, ions and dust charge variations. For this purpose, the current of electrons and ions to the dust surface is calculated, and then the dispersion relation for the dust acoustic waves is obtained. It is shown that by increasing the number of superthermal particles, the growth rate of the instability increases, the dust acoustic waves frequency decreases, and the instability region is extended to the smaller wavelengths. Moreover, it is found that the ratio of the electric force to the self-gravitational force is decreased in the presence of the superthermal particles, and dust charge variations.

  1. The Ridge Associated with the Near-side Jet in High Energy-Heavy-Ion Collisions

    CERN Document Server

    Wong, Cheuk-Yin

    2009-01-01

    The ridge particles associated with a near-side jet are identified as medium partons kicked by the jet near the surface. They carry direct information on the parton momentum distribution at the moment of jet-parton collisions and the magnitude of the longitudinal momentum kick. The extracted early parton momentum distribution has a rapidity plateau structure with a thermal-like transverse momentum distribution. Such a rapidity plateau structure may arise from particle production in flux tubes, as color charges and anti-color charges separate at high energies.

  2. Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    By using the isospin dependent quantum molecular dynamics model (IQMD), we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size, initial N/Z, isospin symmetry potential and the medium correction of two-body cross sections. We find the effect of initial N/Z ratio, isospin symmetry potential on stopping is weak. The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections and the equation of state of nuclear matter (EOS). Our results show the behavior of the excitation function of Qzz/A and

  3. Transverse energy distributions in nucleus-nucleus collisions at 200 GeV/nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Baglin, C.; Baldisseri, A.; Bussiere, A.; Guillaud, J.P.; Kossakowski, R.; Liaud, P.; Staley, F. (Institut National de Physique Nucleaire et de Physique des Particules, 74 - Annecy-le-Vieux (France). Lab. de Physique des Particules); Baldit, A.; Castor, J.; Chambon, T.; Devaux, A.; Fargeix, J.; Felgeyrolles, X.; Force, P.; Fredj, L.; Landaud, G.; Vazeille, F. (Institut National de Physique Nucleaire et de Physique des Particules, 63 - Clermont-Ferrand (France). Lab. de Physique Corpusculaire Clermont-Ferrand-2 Univ., 63 - Aubiere (France)); Sonderegger, P. (European Organization for Nuclear Research, Geneva (Switzerland)); Abreu, M.C.; Bordalo, P.; Ferreira, R.; Gago, J.M.; Lourenco, C.; Peralta, L.; Pimenta, M.; Ramos, S.; Silva, S.; Varela, J. (LIP, Lisbon (Portugal)); Gerschel, C.; Jouan, D.; Papillon, S.; Tarrago, X. (Institut National de Physique Nucleaire et de Physique des Particules, 91 - Orsay (France). Inst. de Physique Nucleaire Paris-11 Univ., 91 - Orsay (France)); Bus; NA38 Collaboration

    1990-11-22

    The transverse energy E{sub T} distributions of nucleus-nucleus collisions are studied in the framework of a simple geometrical model. The distributions for inclusive production of J/{psi} and muon pairs in the mass continuum are analyzed. The shape of the E{sub T} distribution of the continuum agrees with the model. The previously observed decrease of the ratio (J/{psi})/continuum with increasing E{sub T} is due to the behavior of the J/{psi}. (orig.).

  4. Public repository with Monte Carlo simulations for high-energy particle collision experiments

    CERN Document Server

    Chekanov, S V

    2016-01-01

    Planning high-energy collision experiments for the next few decades requires extensive Monte Carlo simulations in order to accomplish physics goals of these experiments. Such simulations are essential for understanding fundamental physics processes, as well as for setting up the detector parameters that help establish R&D projects required over the next few decades. This paper describes a public repository with Monte Carlo event samples before and after detector-response simulation. The goal of this repository is to facilitate the accomplishment of many goals in planning a next generation of particle experiments.

  5. Azimuthal asymmetries in high-energy collisions of protons with holographic shockwaves

    CERN Document Server

    Noronha, Jorge

    2014-01-01

    Large azimuthal quadrupole and octupole asymmetries have recently been found in p+Pb collisions at the LHC. We argue that these might arise from a projectile dipole scattering off randomly shaped intrinsic fluctuations in the target with a size on the order of the dipole. Generic energy-momentum fluctuations generate comparable asymmetries for all multipole moments $v_n$. The holographic description of this process involves the calculation of a light-like Wilson loop in the background of a non-uniform holographic shockwave in the presence of a Neveu-Schwarz 2-form.

  6. Jet Quenching in High Energy Heavy Ion Collisions by QCD Synchrotron-like Radiation

    CERN Document Server

    Shuryak, E V

    2003-01-01

    We consider synchrotron-like radiation in QCD by generalizing Schwinger's treatment of quantum synchrotron radiation in QED to the case of a constant chromomagnetic field. We suggest a novel mechanism for {\\em jet quenching} in heavy ion collisions, whereby high-$p_t$ partons get depleted through strong (classical) color fields. The latters are encountered in the color glass condensate or in the form of expanding shells of exploding sphalerons. Unlike bremsstrahlung radiation through multiple soft rescattering, synchrotron radiation converts a jet into a wide shower of soft gluons. We estimate the energy loss through this mechanism and suggest that it contributes significantly to the unexpectedly strong jet quenching observed at RHIC.

  7. Model investigation of non-thermal phase transition in high energy collisions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The non-thermal phase transition in high energy collisions is studied in detail in the framework of random cascade model. The relation between the characteristic parameter λq of phase transition and the rank q of moment is obtained using Monte Carlo simulation, and the existence of two phases in self-similar cascading multiparticle systems is shown. The relation between the critical point qc of phase transition on the fluctuation parameter α is obtained and compared with the experimental results from NA22. The same study is carried out also by analytical calculation under central limit approximation. The range of validity of the central limit approximation is discussed.

  8. High-energy photon collisions at the LHC - dream or reality?

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, M. [Laboratoire de Physique Subatomique et de Cosmologie, Universite Joseph Fourier / CNRS-IN2P3 / INPG, 53 Avenue des Martyrs, F-38026 Grenoble (France)

    2008-08-15

    We discuss the potential of high-energy photon collisions at the LHC for improving our understanding of QCD and studying the physics beyond the Standard Model. After reviewing briefly the legacy of past photoproduction experiments at LEP and HERA, we examine the gold-plated channels proposed for a photon collider at the ILC for their potential in a hadron collider environment. We stress that initial-state photon interactions have indeed been observed at RHIC and at the Tevatron. Three promising channels at the LHC are then presented in some detail: vector-meson production, measurements of possibly anomalous electroweak gauge-boson or top-quark couplings, and slepton production.

  9. High-energy photon collisions at the LHC dream or reality?

    Science.gov (United States)

    Klasen, M.

    2008-08-01

    We discuss the potential of high-energy photon collisions at the LHC for improving our understanding of QCD and studying the physics beyond the Standard Model. After reviewing briefly the legacy of past photoproduction experiments at LEP and HERA, we examine the gold-plated channels proposed for a photon collider at the ILC for their potential in a hadron collider environment. We stress that initial-state photon interactions have indeed been observed at RHIC and at the Tevatron. Three promising channels at the LHC are then presented in some detail: vector-meson production, measurements of possibly anomalous electroweak gauge-boson or top-quark couplings, and slepton production.

  10. Intermediate Mass Fragment Emission Pattern in Peripheral Heavy-Ion Collisions at Fermi Energies

    Science.gov (United States)

    Piantelli, S.; Bidini, L.; Poggi, G.; Bini, M.; Casini, G.; Maurenzig, P. R.; Olmi, A.; Pasquali, G.; Stefanini, A. A.; Taccetti, N.

    2002-02-01

    The emission pattern in the vperp-vpar plane of intermediate mass fragments with Z = 3-7 (IMF) has been studied in the collision 116Sn+ 93Nb at 29.5A MeV as a function of the total kinetic energy loss of the reaction. This pattern shows that for peripheral reactions most IMF's are emitted at velocities intermediate between those of the projectile- and target-like products. Coulomb trajectory calculations show that these IMF's are produced in the interaction zone in a short time interval at the end of the target-projectile interaction.

  11. Strangeness production in high-energy collisions and Hawking-Unruh radiation

    Science.gov (United States)

    Tawfik, Abdel Nasser; Yassin, Hayam; Abo Elyazeed, Eman R.

    The assumption that the production of quark-antiquark pairs and their sequential string-breaking takes place, likely as a tunneling process, through the event horizon of the color confinement determines the freezeout temperature and gives a plausible interpretation for the thermal pattern of elementary and nucleus-nucleus collisions. When relating the black-hole electric charges to the baryon-chemical potentials, it was found that the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in the statistical thermal models and Polyakov linear-sigma model agree well with the ones determined from the thermal radiation from charged black hole. Accordingly, the resulting freezeout conditions, such as normalized entropy density s/T3 = 7 and average energy per particle /≃ 1GeV, are confirmed at finite chemical potentials as well. Furthermore, the problem of strangeness production in elementary collisions can be interpreted by thermal particle production from the Hawking-Unruh radiation. Consequently, the freezeout temperature depends on the quark masses. This leads to a deviation from full equilibrium and thus a suppression of the strangeness production in the elementary collisions. But in nucleus-nucleus collisions, an average temperature should be introduced in order to dilute the quark masses. This nearly removes the strangeness suppression. An extension to finite chemical potentials is introduced. The particle ratios of kaon-to-pion (K+/π+), phi-to-kaon (ϕ/K‑) and antilambda-to-pion (Λ¯/π‑) are determined from Hawking-Unruh radiation and compared with the thermal calculations and the measurements in different experiments. We conclude that these particle ratios can be reproduced, at least qualitatively, as Hawking-Unruh radiation at finite chemical potential. With increasing energy, both K+/π+ and ϕ/K‑ keep their maximum values at low SPS energies. But the further energy

  12. Centrality-dependent forward $J/\\psi$ production in high energy proton-nucleus collisions

    CERN Document Server

    Ducloué, B; Mäntysaari, H

    2016-01-01

    Forward $J/\\psi$ production and suppression in high energy proton-nucleus collisions can be an important probe of gluon saturation. In an earlier work we studied this process in the Color Glass Condensate framework and showed that using the Glauber approach to extrapolate the dipole cross section of a proton to a nucleus leads to results closer to experimental data than previous calculations in this framework. Here we investigate the centrality dependence of the nuclear suppression in this model and show a comparison of our results with recent LHC data.

  13. Interferometry imaging for the evolving source in heavy ion collisions at HIRFL-CSR energy

    Institute of Scientific and Technical Information of China (English)

    YIN Hong-Jie; M. J. Efaaf; ZHANG Wei-Ning

    2012-01-01

    Imaging analysis of two-pion interferometry is performed for an evolving particle-emitting source in heavy ion collisions at HIRFL-CSR energy.The source evolution is described by the relativistic hydrodynamics in (2+1) dimensions. The model-independent characteristic quantities of the source are investigated and compared with the interferometry results obtained by the usual Gaussian formula fit.It is found that the firstorder source function moments can describe the source sizes.The ratio of the normalized standard deviation (O) to the first-order moment (R),(O)/(R),is sensitive to the shape of the source function.

  14. Midrapidity hyperon production in pp and pA collisions from low to LHC energies

    Energy Technology Data Exchange (ETDEWEB)

    Arakelyan, G.H. [Yerevan Physics Institute, A.Alikhanyan National Scientific Laboratory, Yerevan (Armenia); Merino, C. [Universidade de Santiago de Compostela, Departamento de Fisica de Particulas, Facultade de Fisica y Instituto Galego de Fisica de Altas Enerxias (IGFAE), Galiza (Spain); Shabelski, Yu.M. [NCR Kurchatov Institute, Petersburg Nuclear Physics Institute, St. Petersburg (Russian Federation)

    2016-01-15

    The experimental data on p, Λ, Ξ{sup -}, Ω{sup -} -baryons and the corresponding antibaryons spectra obtained by different collaborations are compared with the results of the calculations performed into the frame of the quark-gluon string model. The contribution of string junction diffusion and the inelastic screening corrections are accounted for in the theoretical calculations. The predictions of the quark-gluon string model both for pp and pA collisions are extended up to the LHC energies. (orig.)

  15. Effective equation of state of hot and dense matter in nuclear collisions around FAIR energy

    Directory of Open Access Journals (Sweden)

    Bravina L.

    2015-01-01

    Full Text Available The chemical and thermal equilibration in the central zone of heavy-ion collisions at energies around FAIR is studied within two microscopic models. Two systems are utilized for the analysis: (i central cubic cell of fixed volume V = 125 fm3 and (ii expanding central area of uniformly distributed energy density. It is found that kinetic, thermal, and chemical equilibration of the expanding hadronic matter are nearly approached in both systems for the period of 10–18 fm/c. The expansion proceeds almost isentropically. The extracted equation of state (EOS in P − ɛ plane has a linear dependence P = aɛ, where a ≡ c2s slightly increases with the collision energy from 0.12 to 0.145. Linear dependencies for the EOS are found also in T − μB and T − μS planes. The characteristic kinks observed in the last two phase diagrams are linked to inelastic freeze-out in the expanding fireball.

  16. Chemical reaction versus vibrational quenching in low energy collisions of vibrationally excited OH with O

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, G. B.; Juanes-Marcos, J. C.; Balakrishnan, N., E-mail: naduvala@unlv.nevada.edu [Department of Chemistry, University of Nevada Las Vegas, Las Vegas, Nevada 89154 (United States); Kendrick, Brian K. [Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2013-11-21

    Quantum scattering calculations are reported for state-to-state vibrational relaxation and reactive scattering in O + OH(v = 2 − 3, j = 0) collisions on the electronically adiabatic ground state {sup 2}A′′ potential energy surface of the HO{sub 2} molecule. The time-independent Schrödinger equation in hyperspherical coordinates is solved to determine energy dependent probabilities and cross sections over collision energies ranging from ultracold to 0.35 eV and for total angular momentum quantum number J = 0. A J-shifting approximation is then used to compute initial state selected reactive rate coefficients in the temperature range T = 1 − 400 K. Results are found to be in reasonable agreement with available quasiclassical trajectory calculations. Results indicate that rate coefficients for O{sub 2} formation increase with increasing the OH vibrational level except at low and ultralow temperatures where OH(v = 0) exhibits a slightly different trend. It is found that vibrational relaxation of OH in v = 2 and v = 3 vibrational levels is dominated by a multi-quantum process.

  17. A hadron-nucleus collision event generator for simulations at intermediate energies

    CERN Document Server

    Ackerstaff, K; Bollmann, R

    2002-01-01

    Several available codes for hadronic event generation and shower simulation are discussed and their predictions are compared to experimental data in order to obtain a satisfactory description of hadronic processes in Monte Carlo studies of detector systems for medium energy experiments. The most reasonable description is found for the intra-nuclear-cascade (INC) model of Bertini which employs microscopic description of the INC, taking into account elastic and inelastic pion-nucleon and nucleon-nucleon scattering. The isobar model of Sternheimer and Lindenbaum is used to simulate the inelastic elementary collisions inside the nucleus via formation and decay of the DELTA sub 3 sub 3 -resonance which, however, limits the model at higher energies. To overcome this limitation, the INC model has been extended by using the resonance model of the HADRIN code, considering all resonances in elementary collisions contributing more than 2% to the total cross-section up to kinetic energies of 5 GeV. In addition, angular d...

  18. Initial Energy Density of √s = 7 and 8 TeV p–p Collisions at the LHC

    Directory of Open Access Journals (Sweden)

    Máté Csanád

    2017-02-01

    Full Text Available Results from the Relativistic Heavy Ion Colloder (RHIC and the Large Hadron Collider (LHC experiments show that in relativistic heavy ion collisions, a new state of matter, a strongly interacting perfect fluid, is created. Accelerating, exact and explicit solutions of relativistic hydrodynamics allow for a simple and natural description of this medium. A finite rapidity distribution arises from these solutions, leading to an advanced estimate of the initial energy density of high energy collisions. These solutions can be utilized to describe various aspects of proton–proton collisions, as originally suggested by Landau. We show that an advanced estimate based on hydrodynamics yields an initial energy density in s = 7 and 8 TeV proton–proton (p–p collisions at the LHC on the same order as the critical energy density from lattice Quantum Chromodynamics (QCD. The advanced estimate yields a corresponding initial temperature that is around the critical temperature from QCD and the Hagedorn temperature. The multiplicity dependence of the estimated initial energy density suggests that in high multiplicity p–p collisions at the LHC, there is large enough initial energy density to create a non-hadronic perfect fluid.

  19. Heavy quark pair production in high energy pA collisions: Quarkonium

    CERN Document Server

    Fujii, Hirotsugu

    2013-01-01

    Quarkonium production in high-energy proton (deuteron)-nucleus collisions is investigated in the color glass condensate framework. We employ the color evaporation model assuming that the quark pair produced from dense small-x gluons in the nuclear target bounds into a quarkonium outside the target. The unintegrated gluon distribution at small Bjorken x in the nuclear target is treated with the Balitsky-Kovchegov equation with running coupling corrections. For the gluons in the proton, we examine two possible descriptions, unintegrated gluon distribution and ordinary collinear gluon distribution. We present the transverse momentum spectrum and nuclear modification factor for J/psi production at RHIC and LHC energies, and those for Upsilon(1S) at LHC energy, and discuss the nuclear modification factor and the momentum broadening by changing the rapidity and the initial saturation scale.

  20. Energy dependence of hard bremsstrahlung production in proton-proton collisions in the Delta(1232) region

    CERN Document Server

    Tsirkov, D; Azaryan, T; Chiladze, D; Dymov, S; Dzyuba, A; Hartmann, M; Kacharava, A; Khoukaz, A; Kulikov, A; Kurbatov, V; Macharashvili, G; Merzliakov, S; Mielke, M; Mikirtychiants, S; Nekipelov, M; Rathmann, F; Serdyuk, V; Stroeher, H; Uzikov, Yu; Valdau, Yu; Wilkin, C

    2010-01-01

    Hard bremsstrahlung production in proton-proton collisions has been studied with the ANKE spectrometer at COSY-Juelich in the energy range of 353-800 MeV by detecting the final proton pair {pp}_s from the pp -> {pp}_s reaction with very low excitation energy. Differential cross sections were measured at small diproton c.m. angles from 0 to 20 degrees and the average over this angular interval reveals a broad peak at a beam energy around 650 MeV with a FWHM of about 220 MeV, suggesting the influence of Delta(1232)N intermediate states. Comparison with deuteron photodisintegration shows that the cross section for diproton production is up to two orders of magnitude smaller, due largely to differences in the selection rules.

  1. Energetics of Midvelocity Emissions in Peripheral Heavy Ion Collisions at Fermi Energies

    Science.gov (United States)

    Mangiarotti, A.; Maurenzig, P. R.; Olmi, A.; Piantelli, S.; Bardelli, L.; Bartoli, A.; Bini, M.; Casini, G.; Coppi, C.; Gobbi, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.; Taccetti, N.; Vanzi, E.

    2004-11-01

    Peripheral and semiperipheral collisions have been studied in the system 93Nb+93Nb at 38A MeV. The evaporative and midvelocity components of the light charged particle and intermediate mass fragment emissions have been carefully disentangled. In this way it was possible to obtain the average amount not only of charge and mass, but also of energy, pertaining to the midvelocity emission, as a function of an impact parameter estimator. This emission has a very important role in the overall balance of the reaction, as it accounts for a large fraction of the emitted mass and for more than half of the dissipated energy. As such, it may give precious clues on the microscopic mechanism of energy transport from the interaction zone toward the target and projectile remnants.

  2. A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Kilhung Lee

    2010-03-01

    Full Text Available This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme.

  3. A Time Tree Medium Access Control for Energy Efficiency and Collision Avoidance in Wireless Sensor Networks

    Science.gov (United States)

    Lee, Kilhung

    2010-01-01

    This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme. PMID:22319270

  4. Energetics of midvelocity emissions in peripheral heavy ion collisions at Fermi energies

    CERN Document Server

    Mangiarotti, A; Olmi, A; Piantelli, S; Bardelli, L; Bartoli, A; Bini, M; Casini, G; Coppi, C; Gobbi, A; Pasquali, G; Poggi, G; Stefanini, A A; Taccetti, N; Vanzi, E

    2004-01-01

    Peripheral and semi-peripheral collisions have been studied in the system 93Nb+93Nb at 38 AMeV. The evaporative and midvelocity components of the light charged particle and intermediate mass fragment emissions have been carefully disentangled. In this way it was possible to obtain the average amount not only of charge and mass, but also of energy, pertaining to the midvelocity emission, as a function of an impact parameter estimator. This emission has a very important role in the overall balance of the reaction, as it accounts for a large fraction of the emitted mass and for more than half of the dissipated energy. As such, it may give precious clues on the microscopic mechanism of energy transport from the interaction zone toward the target and projectile remnants.

  5. Energetics of midvelocity emissions in peripheral heavy ion collisions at Fermi energies.

    Science.gov (United States)

    Mangiarotti, A; Maurenzig, P R; Olmi, A; Piantelli, S; Bardelli, L; Bartoli, A; Bini, M; Casini, G; Coppi, C; Gobbi, A; Pasquali, G; Poggi, G; Stefanini, A A; Taccetti, N; Vanzi, E

    2004-12-03

    Peripheral and semiperipheral collisions have been studied in the system 93Nb+93Nb at 38A MeV. The evaporative and midvelocity components of the light charged particle and intermediate mass fragment emissions have been carefully disentangled. In this way it was possible to obtain the average amount not only of charge and mass, but also of energy, pertaining to the midvelocity emission, as a function of an impact parameter estimator. This emission has a very important role in the overall balance of the reaction, as it accounts for a large fraction of the emitted mass and for more than half of the dissipated energy. As such, it may give precious clues on the microscopic mechanism of energy transport from the interaction zone toward the target and projectile remnants.

  6. A time tree medium access control for energy efficiency and collision avoidance in wireless sensor networks.

    Science.gov (United States)

    Lee, Kilhung

    2010-01-01

    This paper presents a medium access control and scheduling scheme for wireless sensor networks. It uses time trees for sending data from the sensor node to the base station. For an energy efficient operation of the sensor networks in a distributed manner, time trees are built in order to reduce the collision probability and to minimize the total energy required to send data to the base station. A time tree is a data gathering tree where the base station is the root and each sensor node is either a relaying or a leaf node of the tree. Each tree operates in a different time schedule with possibly different activation rates. Through the simulation, the proposed scheme that uses time trees shows better characteristics toward burst traffic than the previous energy and data arrival rate scheme.

  7. Particle production in high-energy collisions beyond the shockwave limit

    CERN Document Server

    Altinoluk, Tolga

    2015-01-01

    We compute next to eikonal (NE) and next to next to eikonal (NNE) corrections to the Lipatov vertex due to a finite target thickness. These arise from electric field insertions into the eikonal Wilson lines. We then derive a $k_T$-factorization formula for single inclusive gluon production at NNE accuracy. Our expressions could provide a basis for improved computations of particle production at RHIC energies, and in the backward rapidity region of collisions at LHC energies. First qualitative numerical estimates appear to justify the high-energy coherence approximation for $x\\lsim 0.01$ even for a heavy-ion target. However, beyond $x\\gsim 0.02$ the corrections grow rapidly.

  8. Towards the full quantum description of low-energy reactive collisions of O- with H2

    Science.gov (United States)

    Houfek, Karel; Cizek, Martin

    2016-05-01

    In this contribution we present preliminary results for reactive collisions of O- anions with hydrogen molecules at low energies. The three lowest potential energy surfaces for the anion are calculated for large number of geometries where the electron is bound. The conical intersections of these three states are located together with the intersections with the potential energy surface of the neutral molecule. In the autodetachment region where electron can escape leaving the neutral molecule behind we performed the fixed-nuclei electron scattering calculations using the UK R-matrix codes to obtain input data for construction of the nonlocal resonance model for full quantum description of nuclear dynamics. Classical trajectory calculations of the dynamics are also presented.

  9. Energy and system size dependence of φ meson production in Cu+Cu and Au+Au collisions

    NARCIS (Netherlands)

    Abelev, B.I.; Bai, Y.; Benedosso, F.; Botje, M.A.J.; Braidot, E; Mischke, A.; Peitzmann, T.; Russcher, M.J.; Snellings, R.J.M.; van Leeuwen, M.

    2009-01-01

    We study the beam-energy and system-size dependence of φ meson production (using the hadronic decay mode φ→ K+K−) by comparing the new results from Cu + Cu collisions and previously reported Au+Au collisions at √ sNN = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this

  10. An effective model for entropy deposition in high-energy pp, pA, and AA collisions

    CERN Document Server

    Moreland, J Scott; Bass, Steffen A

    2014-01-01

    We introduce TRENTO, a new initial condition model for high-energy nuclear collisions based on eikonal entropy deposition via a "reduced thickness" function. The model simultaneously predicts the shapes of experimental proton-proton, proton-nucleus, and nucleus-nucleus multiplicity distributions, and generates nucleus-nucleus eccentricity harmonics consistent with experimental flow constraints. In addition, the model provides a possible resolution to the "knee" puzzle in ultra-central uranium-uranium collisions.

  11. Energy and centrality dependence of antiproton and proton production in relativistic Pb+Pb collisions at the CERN SPS

    CERN Document Server

    Alt, C; Baatar, B.; Barna, D.; Bartke, J.; Betev, L.; Bialkowska, H.; Blume, C.; Boimska, B.; Botje, M.; Bracinik, J.; Bramm, R.; Buncic, P.; Cerny, V.; Christakoglou, P.; Chvala, O.; Cramer, J.G.; Csato, P.; Dinkelaker, P.; Eckardt, V.; Flierl, D.; Fodor, Z.; Foka, P.; Friese, V.; Gal, J.; Gazdzicki, M.; Genchev, V.; Georgopoulos, G.; Gladysz, E.; Grebieszkow, K.; Hegyi, S.; Hohne, C.; Kadija, K.; Karev, A.; Kliemant, M.; Kniege, S.; Kolesnikov, V.I.; Kornas, E.; Korus, R.; Kowalski, M.; Kraus, I.; Kreps, M.; Laslo, A.; van Leeuwen, M.; Levai, P.; Litov, L.; Lungwitz, B.; Makariev, M.; Malakhov, A.I.; Mateev, M.; Melkumov, G.L.; Mischke, A.; Mitrovski, M.; Molnar, J.; Mrowczynski, St.; Nicolic, V.; Palla, G.; Panagiotou, A.D.; Panayotov, D.; Petridis, A.; Pikna, M.; Prindle, D.; Puhlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczynski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Sikler, F.; Sitar, B.; Skrzypczak, E.; Stefanek, G.; Stock, R.; Strabel, C.; Strobele, H.; Susa, T.; Szentpetery, I.; Sziklai, J.; Szymanski, P.; Trubnikov, V.; Varga, D.; Vassiliou, M.; Veres, G.I.; Vesztergombi, G.; Vranic, D.; Wetzler, A.; Wlodarczyk, Z.; Yoo, I.K.; Zimanyi, J.

    2005-01-01

    The transverse mass distributions for antiprotons are measured at midrapidity for minimum bias Pb+Pb collisions at 158A GeV and for central Pb+Pb collisions at 20, 30, 40 and 80 A GeV beam energies in the NA49 experiment at the CERN SPS. The rapidity density, inverse slope parameter and mean transverse mass derived from the transverse mass distributions are studied as a function of the incident energy and the collision centrality and compared to the relevant proton data. The shapes of the m_T distributions of antiprotons and protons are very similar. The ratios of the particle yields, antiproton/proton and antilambda/antiproton, are also analysed. The antiproton/proton ratio exhibits an increase with diminishing centrality and a steep rise with increasing beam energy. The antilambda/antiproton ratio increases beyond unity with decreasing beam energy.

  12. Observation of Scattering Resonances in the Penning Ionization of NH$_3$ by He($^3$S$_1$) at Low Collision Energies

    CERN Document Server

    Jankunas, Justin; Hapka, Michal; Osterwalder, Andreas

    2014-01-01

    A merged-beam study of the gas phase He($^3$S$_1$) + NH$_3$ Penning ionization reaction dynamics in the collision energy range 3.3 $\\mu$eV $<$ E $<$ 10 meV is presented. In this energy range the reaction rate is governed by long-range attraction. Shape resonances are observed at collision energies of 1.8 meV and 7.3 meV and are assigned to $\\ell$=15,16 and $\\ell$=20,21 partial waves, respectively. The experimental results are well reproduced by theoretical calculations with the short-range reaction probability $P_{sr}=0.035$.

  13. Collision energy dependence of elliptic flow splitting between particles and their antiparticles from an extended multiphase transport model

    CERN Document Server

    Xu, Jun

    2016-01-01

    Based on an extended multiphase transport model, which includes mean-field potentials in both the partonic and hadronic phases, uses the mix-event coalescence, and respects charge conservation during the hadronic evolution, we have studied the collision energy dependence of the elliptic flow splitting between particles and their antiparticles. This extended transport model reproduces reasonably well the experimental data at lower collision energies but only describes qualitatively the elliptic flow splitting at higher beam energies. The present study thus indicates the existence of other mechanisms for the elliptic flow splitting besides the mean-field potentials and the need of further improvements of the multiphase transport model.

  14. Energy dependence of elliptic flow over a large pseudorapidity range in Au+Au collisions at RHIC

    CERN Document Server

    Back, B B; Ballintijn, M; Barton, D S; Betts, R R; Bickley, A A; Bindel, R; Budzanowski, A; Busza, W; Carroll, A; Chai, Z; Decowski, M P; García, E; Gburek, T; George, N; Gulbrandsen, K H; Gushue, S; Halliwell, C; Hamblen, J; Hauer, M; Heintzelman, G A; Henderson, C; Hofman, D J; Hollis, R S; Holynski, R; Holzman, B; Iordanova, A; Johnson, E; Kane, J L; Katzy, J; Khan, N; Kucewicz, W; Kulinich, P; Kuo, C M; Lin, W T; Manly, S; McLeod, D; Mignerey, A C; Nouicer, R; Olszewski, A; Pak, R; Park, I C; Pernegger, H; Reed, C; Remsberg, L P; Reuter, M; Roland, C; Roland, G; Rosenberg, L J; Sagerer, J; Sarin, P; Sawicki, P; Seals, H; Sedykh, I; Skulski, W; Smith, C E; Stankiewicz, M A; Steinberg, P; Stephans, G S F; Sukhanov, A; Tang, J L; Tonjes, M B; Trzupek, A; Vale, C; van Nieuwenhuizen, G J; Vaurynovich, S S; Verdier, R; Veres, G I; Wenger, E; Wolfs, F L H; Wosiek, B; Wozniak, K; Wuosmaa, A H; Wyslouch, B

    2004-01-01

    This paper describes the measurement of the energy dependence of elliptic flow for charged particles in Au+Au collisions using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). Data taken at collision energies of $\\sqrt{s_{_{NN}}} =$ 19.6, 62.4, 130 and 200 GeV are shown over a wide range in pseudorapidity. These results, when plotted as a function of $\\eta'=|\\eta|-y_{beam}$, scale with approximate linearity throughout $\\eta'$, implying no sharp changes in the dynamics of particle production as a function of pseudorapidity or increasing beam energy.

  15. Subcascade formation and defect cluster size scaling in high-energy collision events in metals

    Science.gov (United States)

    De Backer, A.; Sand, A. E.; Nordlund, K.; Luneville, L.; Simeone, D.; Dudarev, S. L.

    2016-07-01

    It has been recently established that the size of the defects created under ion irradiation follows a scaling law (Sand A. E. et al., EPL, 103 (2013) 46003; Yi X. et al., EPL, 110 (2015) 36001). A critical constraint associated with its application to phenomena occurring over a broad range of irradiation conditions is the limitation on the energy of incident particles. Incident neutrons or ions, with energies exceeding a certain energy threshold, produce a complex hierarchy of collision subcascade events, which impedes the use of the defect cluster size scaling law derived for an individual low-energy cascade. By analyzing the statistics of subcascade sizes and energies, we show that defect clustering above threshold energies can be described by a product of two scaling laws, one for the sizes of subcascades and the other for the sizes of defect clusters formed in subcascades. The statistics of subcascade sizes exhibits a transition at a threshold energy, where the subcascade morphology changes from a single domain below the energy threshold, to several or many sub-domains above the threshold. The number of sub-domains then increases in proportion to the primary knock-on atom energy. The model has been validated against direct molecular-dynamics simulations and applied to W, Fe, Be, Zr and sixteen other metals, enabling the prediction of full statistics of defect cluster sizes with no limitation on the energy of cascade events. We find that populations of defect clusters produced by the fragmented high-energy cascades are dominated by individual Frenkel pairs and relatively small defect clusters, whereas the lower-energy non-fragmented cascades produce a greater proportion of large defect clusters.

  16. Exclusive quarkonium photoproduction in proton-lead collisions at LHC energies

    Energy Technology Data Exchange (ETDEWEB)

    Santos, G.S. dos; Machado, M.V.T. [Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    2013-07-01

    Full text: In this work we study the exclusive photoproduction of J/ aΨ and ϒ mesons in the ultrarelativistic proton-nucleus interactions at the LHC energies and analyze if these processes can be used to determine the QCD dynamics at high energies. Exclusive vector meson production is a useful process providing important information on the transition region between soft and hard QCD regime. It is expected that electromagnetic interactions be dominant at ultrarelativistic heavy ion collisions at large impact parameter of interaction. These collisions are characterized by restricting in the impact parameter b, where the requirement can be done for b to be larger than the sum of the hadron and nuclear target radius. The gain in studying photon induced interactions is the high equivalent photon energies that is achieved at LHC kinematic range. The theoretical approach considered in the present work is the color dipole picture, describing the quasi-real photon interaction with the nucleus target. In such a scenario, the projectile has just enough energy to fluctuate into a quark-antiquark pair long before the scattering. Furthermore, these pairs with transverse separation r interacts with the target as color singlet dipole. We calculate the integrated cross section and rapidity distribution within the QCD color dipole approach, providing theoretical prediction for the recent proton-lead run at the LHC for the energy of 5 TeV. A comparison with the linear dynamics predictions is also presented. Our results indicate that the nonlinear dynamics can be proven in those reactions, which are well suited for studying saturation effects. (author)

  17. Kinetic energy release of dissociating CO3+ ions produced in collisions of multiply charged ions with CO

    NARCIS (Netherlands)

    Schlatholter, T; Hoekstra, R; Morgenstern, R

    1997-01-01

    We investigate fragmentation of CO molecules by collisions of He2+ ions at energies between 2 and 11 keV/amu by means of a reflectron time-of-flight (TOF) spectrometer. The kinetic-energy-release (KER) in the center of mass system of the molecule can be determined from the flight times of these

  18. Chiral symmetry restoration in heavy-ion collisions at intermediate energies

    Science.gov (United States)

    Palmese, A.; Cassing, W.; Seifert, E.; Steinert, T.; Moreau, P.; Bratkovskaya, E. L.

    2016-10-01

    We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range √{sN N}=3 -20 GeV within the parton-hadron-string dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the nonlinear σ -ω model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations. For the pion-nucleon Σ term we adopt Σπ≈ 45 MeV, which corresponds to some world average. Our systematic studies show that chiral symmetry restoration plays a crucial role in the description of heavy-ion collisions at √{sN N}=3 -20 GeV, realizing an increase of the hadronic particle production in the strangeness sector with respect to the nonstrange one. We identify particle abundances and rapidity spectra to be suitable probes in order to extract information about CSR, while transverse mass spectra are less sensitive. Our results provide a microscopic explanation for the so-called horn structure in the excitation function of the K+/π+ ratio: The CSR in the hadronic phase produces the steep increase of this particle ratio up to √{sN N}≈7 GeV, while the drop at higher energies is associated to the appearance of a deconfined partonic medium. Furthermore, the appearance and disappearance of the horn-structure are investigated as functions of the system size and collision centrality. We close this work by an analysis of strangeness production in the (T ,μB ) plane (as extracted from the PHSD for central Au+Au collisions) and discuss the possibilities to identify a possible critical point in the phase diagram.

  19. The first moment of azimuthal anisotropy in nuclear collisions from AGS to LHC energies

    CERN Document Server

    Singha, Subhash; Keane, Declan

    2016-01-01

    We review topics related to the first moment of azimuthal anisotropy ($v_1$), commonly known as directed flow, focusing on both charged particles and identified particles from heavy-ion collisions. Beam energies from the highest available, at the CERN LHC, down to projectile kinetic energies per nucleon of a few GeV per nucleon, as studied in experiments at the Brookhaven AGS, fall within our scope. We focus on experimental measurements and on theoretical work where direct comparisons with experiment have been emphasized. The physics addressed or potentially addressed by this review topic includes the study of Quark Gluon Plasma, and more generally, investigation of the Quantum Chromodynamics phase diagram and the equation of state describing the accessible phases.

  20. Distinctive features of Coulomb-related emissions in peripheral heavy ion collisions at Fermi energies

    CERN Document Server

    Piantelli, S; Olmi, A; Bardelli, L; Bini, M; Casini, G; Mangiarotti, A; Pasquali, G; Poggi, G; Stefanini, A A

    2007-01-01

    Light charged particles emitted at about 90 deg in the frame of the projectile-like fragment in semi-peripheral collisions of 93Nb+93Nb at 38A MeV give evidence for the simultaneous occurrence of two different production mechanisms. This is demonstrated by differences in the kinetic energy spectra and in the isotopic composition of the particles. The emission with a softer kinetic energy spectrum and a low N/Z ratio for the hydrogen isotopes is attributed to an evaporation process. The harder emission, with a much higher N/Z ratio, can be attributed to a ``midvelocity'' process consisting of a non-isotropic emission, on a short time-scale, from the surface of the projectile-like fragment.

  1. Degree of Chemical Non-equilibrium in Central Au-Au Collisions at RHIC energies

    CERN Document Server

    Tawfik, Abdel Nasser; Habashy, D M; Mohamed, M T; Abbas, Ehab

    2014-01-01

    We investigate the difference between hadron resonance gas (HRG) calculations for chemical freeze-out parameters at fully and partly chemical equilibria. To this end, the results are compared with the particle ratios measured in central Au-Au collisions at a wide range of nucleon-nucleon center-of-mass energies, \\hbox{$\\sqrt{s_{NN}}=7.7-200 $GeV} as offered by the STAR experiment. We restrict the discussion to STAR, because of large statistics and overall homogeneity of STAR measurements (one detector) against previous experiments. We find that the matter produced at these energies is likely in fully chemical equilibrium, which is consistent with recent lattice QCD results. The possible improvements by partial chemical equilibrium ($\\gamma_S\

  2. A new relativistic hydrodynamics code for high-energy heavy-ion collisions

    Science.gov (United States)

    Okamoto, Kazuhisa; Akamatsu, Yukinao; Nonaka, Chiho

    2016-10-01

    We construct a new Godunov type relativistic hydrodynamics code in Milne coordinates, using a Riemann solver based on the two-shock approximation which is stable under the existence of large shock waves. We check the correctness of the numerical algorithm by comparing numerical calculations and analytical solutions in various problems, such as shock tubes, expansion of matter into the vacuum, the Landau-Khalatnikov solution, and propagation of fluctuations around Bjorken flow and Gubser flow. We investigate the energy and momentum conservation property of our code in a test problem of longitudinal hydrodynamic expansion with an initial condition for high-energy heavy-ion collisions. We also discuss numerical viscosity in the test problems of expansion of matter into the vacuum and conservation properties. Furthermore, we discuss how the numerical stability is affected by the source terms of relativistic numerical hydrodynamics in Milne coordinates.

  3. A new relativistic hydrodynamics code for high-energy heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Kazuhisa [Nagoya University, Department of Physics, Nagoya (Japan); Akamatsu, Yukinao [Nagoya University, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya (Japan); Osaka University, Department of Physics, Toyonaka (Japan); Stony Brook University, Department of Physics and Astronomy, Stony Brook, NY (United States); Nonaka, Chiho [Nagoya University, Department of Physics, Nagoya (Japan); Nagoya University, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya (Japan); Duke University, Department of Physics, Durham, NC (United States)

    2016-10-15

    We construct a new Godunov type relativistic hydrodynamics code in Milne coordinates, using a Riemann solver based on the two-shock approximation which is stable under the existence of large shock waves. We check the correctness of the numerical algorithm by comparing numerical calculations and analytical solutions in various problems, such as shock tubes, expansion of matter into the vacuum, the Landau-Khalatnikov solution, and propagation of fluctuations around Bjorken flow and Gubser flow. We investigate the energy and momentum conservation property of our code in a test problem of longitudinal hydrodynamic expansion with an initial condition for high-energy heavy-ion collisions. We also discuss numerical viscosity in the test problems of expansion of matter into the vacuum and conservation properties. Furthermore, we discuss how the numerical stability is affected by the source terms of relativistic numerical hydrodynamics in Milne coordinates. (orig.)

  4. Single heavy lepton production in high energy electron-positron collisions

    CERN Document Server

    D'Almeida, F; Ramalho, A J; Lopes, J H; Ramalho, A J

    1994-01-01

    The production and decay of exotic leptons are discussed in the context of the vector singlet, vector doublet and fer\\-mion mirror-fer\\-mion models, at c.m. energies \\sqrt{s}=190GeV (LEP II) and \\sqrt{s}=500GeV (NLC). The model dependence of total cross sections and kinematic distributions at these energies is shown to be weak for these three extended models, indicating that it would be difficult to establish which of them is best fit to describe the underlying new physics, should exotic leptons be detected. We suggest that, in order to resolve this difficulty, one should measure the angular distributions of single exotic leptons in longitudinally polarized e^+e^- collisions.

  5. A new relativistic hydrodynamics code for high-energy heavy-ion collisions

    CERN Document Server

    Okamoto, Kazuhisa; Nonaka, Chiho

    2016-01-01

    We construct a new Godunov type relativistic hydrodynamics code in Milne coordinates, using a Riemann solver based on the two-shock approximation which is stable under existence of large shock waves. We check the correctness of the numerical algorithm by comparing numerical calculations and analytical solutions in various problems, such as shock tubes, expansion of matter into the vacuum, Landau-Khalatnikov solution, propagation of fluctuations around Bjorken flow and Gubser flow. We investigate the energy and momentum conservation property of our code in a test problem of longitudinal hydrodynamic expansion with an initial condition for high-energy heavy-ion collisions.We also discuss numerical viscosity in the test problems of expansion of matter into the vacuum and conservation properties. Furthermore, we discuss how the numerical stability is affected by the source terms of relativistic numerical hydrodynamics in Milne coordinates.

  6. Distinctive features of Coulomb-related emissions in peripheral heavy ion collisions at Fermi energies

    Science.gov (United States)

    Piantelli, S.; Maurenzig, P. R.; Olmi, A.; Bardelli, L.; Bini, M.; Casini, G.; Mangiarotti, A.; Pasquali, G.; Poggi, G.; Stefanini, A. A.

    2007-12-01

    Light charged particles emitted at about 90° in the frame of the projectile-like fragment in semiperipheral collisions of Nb93+Nb93 at 38A MeV give evidence for the occurrence, in the same class of events, of two different production mechanisms. This is demonstrated by differences in the kinetic energy spectra and in the isotopic composition of the particles. The emission with a softer kinetic energy spectrum and a low N/Z ratio for the hydrogen isotopes is attributed to an evaporation process. The harder emission, with a much higher N/Z ratio, can be attributed to a midvelocity process consisting of a nonisotropic emission, on a short time-scale, from the projectile-like fragment.

  7. Background and Energy Deposition Studies for the CLIC Post-Collision Line

    CERN Document Server

    Appleby, R B; Deacon, L C; Gschwendtner, E

    2011-01-01

    After the interaction point, the 1.5 TeV, 14MW CLIC electron/positron beams must be transported safely to the main beam dump. In designing the CLIC post-collision line detailed simulations must be carried out in order to ensure that losses are kept within reasonable limits. Results for back-scattered photon flux arriving at the detector are recalculated after updates and enhancements to the geometry description used in the study presented in [1]. Initial results of neutron fluxes are presented. Additionally, energy deposition calculations are carried out, showing that, when the full electromagnetic showers are included, in the current design the standard magnet coils would have a short lifetime due to radiation damage to conventional insulation material. Changing the magnet mask material from graphite to iron and lengthening the intermediate dump by 2m of iron are shown to substantially lessen the energy deposition in the magnet coils and thereby extend magnet lifetimes.

  8. Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris

    CERN Document Server

    Wildner, E; Cerutti, F; Ferrari, A; Hoa, C; Koutchouk, Jean-Pierre; Mokhov, N V

    2008-01-01

    The 14 TeV center of mass proton-proton collisions in the LHC produce not only debris interesting for physics but also showers of particles ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of this contribution to the heat, that has to be transported by the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC base-line are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of code comparison for a reduced setup was made.

  9. Experimental and phenomenological investigations of QCD matter in high-energy nucleus-nucleus collisions

    Energy Technology Data Exchange (ETDEWEB)

    Andronic, Anton

    2014-07-15

    This thesis is heterogeneous, comprising experimental papers at low energies (SIS-18 at GSI) and at the LHC, papers on phenomenology of high-energy nucleus-nucleus collisions, and papers on detectors. The overview covers the experimental papers and those on phenomenology. I have chosen to write it in a general manner, intended to be accessible to non-experts. It emphasizes recent measurements and their understanding at the LHC. The detector papers, which address many principle aspects of gaseous detectors, are summarized and placed in context in the review I co-wrote and which closes the stack. The detector papers included here are the outcome of an R and D program for the Transition Radiation Detector of ALICE.

  10. Rotational Energy Transfer Cross Sections in N2-N2 Collisions

    Science.gov (United States)

    Huo, Winifred M.; Green, Sheldon; Langhoff, Stephen R. (Technical Monitor)

    1995-01-01

    Rotational inelastic transitions of N2 have been studied in the coupled state (CS, also called centrifugal sudden) and infinite-order-sudden (IOS) approximations, using the N2-N2 rigid-rotor potential of van der Avoird et al. For benchmarking purposes, close coupling (CC) calculations have also been carried out over a limited energy range and for even j - even j collisions only. Both the CC and CS cross sections have been obtained with and without exchange symmetry, whereas exchange is neglected in the IOS calculations. The CS results track the CC cross sections rather well. At total energies between 113 to 219 cm(exp -1) the average deviation is 14%. The deviation decrease with increasing energy, indicating that the CS approximation can be used as a substitute at higher energies when the CC calculations become impractical. Comparison between the CS and IOS cross sections at the high energy end of the CS calculation, 500 - 680 cm(exp-1), shows significant differences between the two. In addition, the IOS results exhibits sensitivity to the amount of inelasticity and the results for large DELTA J transitions are subjected to bigger errors. At total energy 113 cm(exp -1) and above, the average deviation between state-to-state cross sections calculated with even and odd exchange symmetries is 1.5%.

  11. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC.

    Science.gov (United States)

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, E C; Attri, A; Averichev, G S; Bai, X; Bairathi, V; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandenburg, J D; Brandin, A V; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chatterjee, A; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A I; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Horvat, S; Huang, T; Huang, X; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jentsch, A; Jia, J; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikoła, D P; Kisel, I; Kisiel, A; Kochenda, L; Koetke, D D; Kosarzewski, L K; Kraishan, A F; Kravtsov, P; Krueger, K; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, X; Li, C; Li, X; Li, Y; Li, W; Lin, T; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, R; Ma, G L; Ma, Y G; Ma, L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Matis, H S; McDonald, D; McKinzie, S; Meehan, K; Mei, J C; Minaev, N G; Mioduszewski, S; Mishra, D; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Niida, T; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V A; Olvitt, D; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Pile, P; Pluta, J; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, A; Sharma, B; Sharma, M K; Shen, W Q; Shi, Z; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Singha, S; Skoby, M J; Smirnov, N; Smirnov, D; Solyst, W; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B; Sun, Z; Sun, X M; Sun, Y; Surrow, B; Svirida, D N; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A; Thäder, J; Thomas, J H; Timmins, A R; Tlusty, D; Todoroki, T; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbæk, F; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, G; Wang, J S; Wang, H; Wang, Y; Wang, Y; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xiao, Z G; Xie, W; Xie, G; Xin, K; Xu, Y F; Xu, Q H; Xu, N; Xu, H; Xu, Z; Xu, J; Yang, S; Yang, Y; Yang, Y; Yang, C; Yang, Y; Yang, Q; Ye, Z; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, Y; Zhang, J; Zhang, J; Zhang, S; Zhang, S; Zhang, Z; Zhang, J B; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2016-03-18

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from sqrt[s_{NN}]=7.7 to 200 GeV. The third harmonic v_{3}^{2}{2}=⟨cos3(ϕ_{1}-ϕ_{2})⟩, where ϕ_{1}-ϕ_{2} is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη=η_{1}-η_{2}. Nonzero v_{3}^{2}{2} is directly related to the previously observed large-Δη narrow-Δϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v_{3}^{2}{2} persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v_{3}^{2}{2} is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v_{3}^{2}{2} for central collisions shows a minimum near sqrt[s_{NN}]=20  GeV.

  12. Differential flow of protons in Au+Au collisions at AGS energies

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, P.K. E-mail: pradip@iopb.res.in; Cassing, W

    2002-12-30

    We study the proton sideward and elliptic differential flow for Au+Au collisions at AGS energies (2-8 A GeV) in a microscopic relativistic transport model that includes all baryon resonances up to a mass of 2 GeV as well as string degrees of freedom for the higher hadronic excitations. In order to explore the sensitivity of the various differential flows to the nuclear equation of state (EoS) we use three different parameterizations of the scalar and vector mean-fields, i.e., NL2 (soft), NL23 (medium) and NL3 (hard), with their momentum dependence fitted to the experimental Schroedinger equivalent potential (at normal nuclear matter density {rho}{sub 0}) up to kinetic energies of 1 GeV. We calculate the excitation function of sideward and elliptic flow within these parameter sets for Au+Au collisions and compare with the recent data from the E895 Collaboration as a function of rapidity, impact parameter and transverse momentum, respectively. We find that the best description of the differential data is provided by a rather 'stiff' EoS at 2 A GeV (NL3) while at higher bombarding energies (4-8 A GeV) a 'medium' EoS leads to the lowest {chi}{sup 2} with respect to the data. However, the differences in the transverse and elliptic flows (from the different parameter sets) become of minor significance at 4-8 A GeV. We attribute this insensitivity to a similar reduction of the vector potential in all models and to the dominance of string degrees of freedom at these bombarding energies.

  13. Initial energy density of $\\sqrt{s}=$ 7 and 8 TeV p+p collisions at the LHC

    CERN Document Server

    Csanad, Mate; Jiang, Ze-Fang; Yan, Chun-Bin

    2016-01-01

    Accelerating, exact, explicit and simple solutions of relativistic hydrodynamics allow for a simple and natural description of highly relativistic p+p collisions. These solutions yield a finite rapidity distribution, thus they lead to an advanced estimate of the initial energy density of high energy collisions. We show that such an advanced estimate yields an initial energy density in $\\sqrt{s}=$ 7 and 8 TeV p+p collisions at LHC around the critical energy density from lattice QCD, and a corresponding initial temperature around the critical temperature from QCD and the Hagedorn temperature. The multiplicity dependence of the estimated initial energy density suggests that in high multiplicity pp collisions at the LHC, there is large enough initial energy density to create a non-hadronic perfect fluid. %We also show, that several times the critical energy density may have been reached in high %multiplicity events, hinting at a non-hadronic medium created in high multiplicity %$\\sqrt{s}=$ 7 and 8 TeV p+p collisi...

  14. Modulational instability of dust ion-acoustic waves in a magnetized dusty superthermal plasma

    CERN Document Server

    Shalini, A P Misra

    2016-01-01

    The amplitude modulation of three dimensional (3D) dust ion-acoustic wave (DIAW) packets is studied in a collisionless magnetized plasma with inertial positive ions, superthermal electrons and negatively charged immobile dust grains. By using the reductive perturbation technique, a 3D-nonlinear Schr{\\"o}dinger (NLS) equation is derived, which governs the slow modulation of DIAW packets. The latter are found to be stable in the low-frequency $(\\omega\\omega_c$, and the modulational instability (MI) is related to the modulational obliqueness $(\\theta)$. Here, $\\omega~(\\omega_c)$ is the nondimensional wave (ion-cyclotron) frequency. It is shown that the superthermal parameter $\\kappa$, the frequency $\\omega_c$ as well as the charged dust impurity $(0<\\mu<1)$ shift the MI domains around the $\\omega-\\theta$ plane, where $\\mu$ is the ratio of electron to ion number densities. Furthermore, it is found that the decay rate of instability is quenched by the superthermal parameter $\\kappa$ with cut-offs at lower wa...

  15. Dust ion-acoustic shock waves due to dust charge fluctuation in a superthermal dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Alinejad, H., E-mail: alinejad@nit.ac.ir [Department of Physics, Faculty of Basic Science, Babol University of Technology, Babol 47148-71167 (Iran, Islamic Republic of); Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Tribeche, M. [Plasma Physics Group, Faculty of Sciences – Physics, University of Bab-Ezzouar (Algeria); Mohammadi, M.A. [Research Institute for Fundamental Sciences (RIFS), University of Tabriz, 51664, Tabriz (Iran, Islamic Republic of); Department of Atomic and Molecular Physics, Faculty of Physics, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2011-11-14

    The nonlinear propagation of dust ion-acoustic (DIA) shock waves is studied in a charge varying dusty plasma with electrons having kappa velocity distribution. We use hot ions with equilibrium streaming speed and a fast superthermal electron charging current derived from orbit limited motion (OLM) theory. It is found that the presence of superthermal electrons does not only significantly modify the basic properties of shock waves, but also causes the existence of shock profile with only positive potential in such plasma with parameter ranges corresponding to Saturn's rings. It is also shown that the strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. -- Highlights: ► The presence of superthermal electrons causes the existence of shock waves with only positive potential. ► The strength and steepness of the shock waves decrease with increase of the size of dust grains and ion temperature. ► As the electrons evolve toward their thermodynamic equilibrium, the shock structures are found with smaller amplitude.

  16. Kinetic Alfv\\'{e}n solitary and rogue waves in superthermal plasmas

    CERN Document Server

    Bains, A; Xia, L -D

    2014-01-01

    We investigate the small but finite amplitude solitary Kinetic Alfv\\'{e}n waves (KAWs) in low $\\beta$ plasmas with superthermal electrons modeled by a kappa-type distribution. A nonlinear Korteweg-de Vries (KdV) equation describing the evolution of KAWs is derived by using the standard reductive perturbation method. Examining the dependence of the nonlinear and dispersion coefficients of the KdV equation on the superthermal parameter $\\kappa$, plasma $\\beta$ and obliqueness of propagation, we show that these parameters may change substantially the shape and size of solitary KAW pulses. Only sub-Alfv\\'enic, compressive solitons are supported. We then extend the study to examine kinetic Alfv\\'en rogue waves by deriving a nonlinear Schr\\"{o}dinger equation from {the KdV} equation. Rational solutions that form rogue wave envelopes are obtained. We examine how the behavior of rogue waves depends on the plasma parameters in question, finding that the rogue envelopes are lowered with increasing electron superthermal...

  17. Oblique ion-acoustic cnoidal waves in two temperature superthermal electrons magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, A., E-mail: anurajrajput@gmail.com; Ryu, C. M., E-mail: ryu201@postech.ac.kr [POSTECH, Hyoja-Dong San 31, KyungBuk, Pohang 790-784 (Korea, Republic of); Bains, A. S., E-mail: bainsphysics@yahoo.co.in [Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, School of Space Science and Physics, Shandong University at Weihai, 264209 Weihai (China)

    2014-12-15

    A study is presented for the oblique propagation of ion acoustic cnoidal waves in a magnetized plasma consisting of cold ions and two temperature superthermal electrons modelled by kappa-type distributions. Using the reductive perturbation method, the nonlinear Korteweg de-Vries equation is derived, which further gives the solutions with a special type of cnoidal elliptical functions. Both compressive and rarefactive structures are found for these cnoidal waves. Nonlinear periodic cnoidal waves are explained in terms of plasma parameters depicting the Sagdeev potential and the phase curves. It is found that the density ratio of hot electrons to ions μ significantly modifies compressive/refractive wave structures. Furthermore, the combined effects of superthermality of cold and hot electrons κ{sub c},κ{sub h}, cold to hot electron temperature ratio σ, angle of propagation and ion cyclotron frequency ω{sub ci} have been studied in detail to analyze the height and width of compressive/refractive cnoidal waves. The findings in the present study could have important implications in understanding the physics of electrostatic wave structures in the Saturn's magnetosphere where two temperature superthermal electrons are present.

  18. Beam-energy dependence of charge balance functions from Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, J. H.; Chen, H. F.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Cui, X.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Filip, P.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, X.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, Z. M.; Li, X.; Li, W.; Li, Y.; Li, X.; Li, C.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, R. M.; Ma, Y. G.; Magdy, N.; Mahapatra, D. P.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Simko, M.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X. M.; Sun, Z.; Sun, Y.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, H.; Wang, F.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, Z.; Xu, H.; Xu, Y.; Xu, Q. H.; Yan, W.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Z. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Y.; Zhang, S.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, Y. H.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-08-01

    Balance functions have been measured in terms of relative pseudorapidity (Δ η ) for charged particle pairs at the BNL Relativistic Heavy Ion Collider from Au + Au collisions at √{sNN}=7.7 GeV to 200 GeV using the STAR detector. These results are compared with balance functions measured at the CERN Large Hadron Collider from Pb + Pb collisions at √{sNN}=2.76 TeV by the ALICE Collaboration. The width of the balance function decreases as the collisions become more central and as the beam energy is increased. In contrast, the widths of the balance functions calculated using shuffled events show little dependence on centrality or beam energy and are larger than the observed widths. Balance function widths calculated using events generated by UrQMD are wider than the measured widths in central collisions and show little centrality dependence. The measured widths of the balance functions in central collisions are consistent with the delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing of the balance function in central collisions at √{sNN}=7.7 GeV implies that a QGP is still being created at this relatively low energy.

  19. Relation between hard photon production and impact parameter in heavy ion collisions at intermediate energies; Dependance de la production de photons durs avec le parametre d`impact dans les collisions entre ions lourds aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Garcia, G.

    1994-06-01

    Hard photons produced in heavy-ions collisions at intermediate energies have been used in order to study hot and compresses nuclear matter created in these collisions (at Ganil). It was found that Bremsstrahlung radiation emitted in np collisions is the main mechanism of hard-photon production for the whole range of impact parameter. Moreover, it was observed a substantial decrease of the hardness of hard-photon spectrum. The BUU model reproduces very well the experimental results, showing that the hardness of the spectrum reflects, mainly, nuclear-matter compression in the first stage of the collision. A new method was developed to measure the density of the nuclear matter created at the beginning of the collision. BUU results and some experimental evidences point out that a significant contribution of hard photons are produced in the last stage of the collision: thermal hard photons. These photons are sensitive to the density oscillation of nuclear matter. Its production cross-section will constitute a measurement of the compressibility of nuclear matter and its spectrum a measure of the temperature. (from author) 64 figs., 60 refs.

  20. Interactions and low energy collisions between an alkali ion and an alkali atom of different nucleus

    CERN Document Server

    Rakshit, Arpita; Berriche, Hamid; Deb, Bimalendu

    2015-01-01

    We study theoretically interaction potentials and low energy collisions between different alkali atoms and alkali ions. Specifically, we consider systems like X + Y$^{+}$, where X(Y$^{+})$ is either Li(Cs$^+$) or Cs((Li$^+$), Na(Cs$^+$) or Cs(Na$^+$) and Li(Rb$^+$) or Rb(Li$^+$). We calculate the molecular potentials of the ground and first two excited states of these three systems using pseudopotential method and compare our results with those obtained by others. We calculate ground-state scattering wave functions and cross sections of these systems for a wide range of energies. We find that, in order to get convergent results for the total scattering cross sections for energies of the order $1$ K, one needs to take into account at least 60 partial waves. In the low energy limit ($< 1 \\mu$K), elastic scattering cross sections exhibit Wigner law threshold behavior while in the high energy limit the cross sections go as $E^{-1/3}$. We discuss qualitatively the possibilities of forming cold molecular ion by ...

  1. A quasi-classical study of energy transfer in collisions of hyperthermal H atoms with SO2 molecules

    Science.gov (United States)

    da Silva, Ramon S.; Garrido, Juan D.; Ballester, Maikel Y.

    2017-08-01

    A deep understanding of energy transfer processes in molecular collisions is at central attention in physical chemistry. Particularly vibrational excitation of small molecules colliding with hot light atoms, via a metastable complex formation, has shown to be an efficient manner of enhancing reactivity. A quasi-classical trajectory study of translation-to-vibration energy transfer (T-V ET) in collisions of hyperthermal H(2S) atoms with SO2(X˜ 1A') molecules is presented here. For such a study, a double many-body expansion potential energy surface previously reported for HSO2(2A) is used. This work was motivated by recent experiments by Ma et al. studying collisions of H + SO2 at the translational energy of 59 kcal/mol [J. Ma et al., Phys. Rev. A 93, 040702 (2016)]. Calculations reproduce the experimental evidence that during majority of inelastic non-reactive collision processes, there is a metastable intermediate formation (HOSO or HSO2). Nevertheless, the analysis of the trajectories shows that there are two distinct mechanisms in the T-V ET process: direct and indirect. Direct T-V processes are responsible for the high population of SO2 with relatively low vibrational excitation energy, while indirect ones dominate the conversion from translational energy to high values of the vibrational counterpart.

  2. Measurement of the pseudorapidity and centrality dependence of the transverse energy density in PbPb collisions at $\\sqrt{s_{NN}}$ = 2.76 TeV

    CERN Document Server

    Chatrchyan, Serguei; Sirunyan, Albert M; Tumasyan, Armen; Adam, Wolfgang; Bergauer, Thomas; Dragicevic, Marko; Erö, Janos; Fabjan, Christian; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hammer, Josef; Hörmann, Natascha; Hrubec, Josef; Jeitler, Manfred; Kiesenhofer, Wolfgang; Knünz, Valentin; Krammer, Manfred; Liko, Dietrich; Mikulec, Ivan; Pernicka, Manfred; Rahbaran, Babak; Rohringer, Christine; Rohringer, Herbert; Schöfbeck, Robert; Strauss, Josef; Taurok, Anton; Wagner, Philipp; Waltenberger, Wolfgang; Walzel, Gerhard; Widl, Edmund; Wulz, Claudia-Elisabeth; Mossolov, Vladimir; Shumeiko, Nikolai; Suarez Gonzalez, Juan; Bansal, Sunil; Cornelis, Tom; De Wolf, Eddi A; Janssen, Xavier; Luyckx, Sten; Maes, Thomas; Mucibello, Luca; Ochesanu, Silvia; Roland, Benoit; Rougny, Romain; Selvaggi, Michele; Staykova, Zlatka; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Blekman, Freya; Blyweert, Stijn; D'Hondt, Jorgen; Gonzalez Suarez, Rebeca; Kalogeropoulos, Alexis; Maes, Michael; Olbrechts, Annik; Van Doninck, Walter; Van Mulders, Petra; Van Onsem, Gerrit Patrick; Villella, Ilaria; Clerbaux, Barbara; De Lentdecker, Gilles; Dero, Vincent; Gay, Arnaud; Hreus, Tomas; Léonard, Alexandre; Marage, Pierre Edouard; Reis, Thomas; Thomas, Laurent; Vander Velde, Catherine; Vanlaer, Pascal; Wang, Jian; Adler, Volker; Beernaert, Kelly; Cimmino, Anna; Costantini, Silvia; Garcia, Guillaume; Grunewald, Martin; Klein, Benjamin; Lellouch, Jérémie; Marinov, Andrey; Mccartin, Joseph; Ocampo Rios, Alberto Andres; Ryckbosch, Dirk; Strobbe, Nadja; Thyssen, Filip; Tytgat, Michael; Verwilligen, Piet; Walsh, Sinead; Yazgan, Efe; Zaganidis, Nicolas; Basegmez, Suzan; Bruno, Giacomo; Castello, Roberto; Ceard, Ludivine; Delaere, Christophe; Du Pree, Tristan; Favart, Denis; Forthomme, Laurent; Giammanco, Andrea; Hollar, Jonathan; Lemaitre, Vincent; Liao, Junhui; Militaru, Otilia; Nuttens, Claude; Pagano, Davide; Pin, Arnaud; Piotrzkowski, Krzysztof; Schul, Nicolas; Vizan Garcia, Jesus Manuel; Beliy, Nikita; Caebergs, Thierry; Daubie, Evelyne; Hammad, Gregory Habib; Alves, Gilvan; Correa Martins Junior, Marcos; De Jesus Damiao, Dilson; Martins, Thiago; Pol, Maria Elena; Henrique Gomes E Souza, Moacyr; Aldá Júnior, Walter Luiz; Carvalho, Wagner; Custódio, Analu; Da Costa, Eliza Melo; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Matos Figueiredo, Diego; Mundim, Luiz; Nogima, Helio; Oguri, Vitor; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Soares Jorge, Luana; Sznajder, Andre; Bernardes, Cesar Augusto; De Almeida Dias, Flavia; Tomei, Thiago; De Moraes Gregores, Eduardo; Lagana, Caio; Da Cunha Marinho, Franciole; Mercadante, Pedro G; Novaes, Sergio F; Padula, Sandra; Genchev, Vladimir; Iaydjiev, Plamen; Piperov, Stefan; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Tcholakov, Vanio; Trayanov, Rumen; Vutova, Mariana; Dimitrov, Anton; Hadjiiska, Roumyana; Kozhuharov, Venelin; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Jiang, Chun-Hua; Liang, Dong; Liang, Song; Meng, Xiangwei; Tao, Junquan; Wang, Jian; Wang, Xianyou; Wang, Zheng; Xiao, Hong; Xu, Ming; Zang, Jingjing; Zhang, Zhen; Asawatangtrakuldee, Chayanit; Ban, Yong; Guo, Shuang; Guo, Yifei; Li, Wenbo; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Teng, Haiyun; Wang, Siguang; Zhu, Bo; Zou, Wei; Avila, Carlos; Gomez, Juan Pablo; Gomez Moreno, Bernardo; Osorio Oliveros, Andres Felipe; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Plestina, Roko; Polic, Dunja; Puljak, Ivica; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Duric, Senka; Kadija, Kreso; Luetic, Jelena; Morovic, Srecko; Attikis, Alexandros; Galanti, Mario; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Finger, Miroslav; Finger Jr, Michael; Assran, Yasser; Elgammal, Sherif; Ellithi Kamel, Ali; Khalil, Shaaban; Mahmoud, Mohammed; Radi, Amr; Kadastik, Mario; Müntel, Mait; Raidal, Martti; Rebane, Liis; Tiko, Andres; Azzolini, Virginia; Eerola, Paula; Fedi, Giacomo; Voutilainen, Mikko; Härkönen, Jaakko; Heikkinen, Mika Aatos; Karimäki, Veikko; Kinnunen, Ritva; Kortelainen, Matti J; Lampén, Tapio; Lassila-Perini, Kati; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Peltola, Timo; Tuominen, Eija; Tuominiemi, Jorma; Tuovinen, Esa; Ungaro, Donatella; Wendland, Lauri; Banzuzi, Kukka; Karjalainen, Ahti; Korpela, Arja; Tuuva, Tuure; Besancon, Marc; Choudhury, Somnath; Dejardin, Marc; Denegri, Daniel; Fabbro, Bernard; Faure, Jean-Louis; Ferri, Federico

    2012-01-01

    The transverse energy ET in PbPb collisions at 2.76 TeV nucleon-nucleon center-of-mass energy sqrt(s[NN]) has been measured over a broad range of pseudorapidity eta and collision centrality using the CMS detector at the LHC. The transverse energy density per unit pseudorapidity d(ET)/d(eta) increases faster with collision energy than the charged particle multiplicity. This implies that the mean energy per particle is increasing with collision energy. At all pseudorapidities the transverse energy per participating nucleon increases with the centrality of the collision. The ratio of transverse energy per unit pseudorapidity in peripheral to central collisions varies significantly as the pseudorapidity increases from eta = 0 to abs(eta) = 5.0. For the most central collisions the energy density per unit volume is estimated to be about 15 GeV/fm^3 at a time of 1 fm/c after the collision. This is about 100 times larger than normal nuclear matter density and a factor of 2.8 times higher than the energy density repor...

  3. Measurement of the Pseudorapidity and Centrality Dependence of the Transverse Energy Density in Pb-Pb Collisions at sNN=2.76TeV

    Science.gov (United States)

    Chatrchyan, S.; Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Fabjan, C.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hammer, J.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Kiesenhofer, W.; Knünz, V.; Krammer, M.; Liko, D.; Mikulec, I.; Pernicka, M.; Rahbaran, B.; Rohringer, C.; Rohringer, H.; Schöfbeck, R.; Strauss, J.; Taurok, A.; Wagner, P.; Waltenberger, W.; Walzel, G.; Widl, E.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Bansal, S.; Cornelis, T.; De Wolf, E. A.; Janssen, X.; Luyckx, S.; Maes, T.; Mucibello, L.; Ochesanu, S.; Roland, B.; Rougny, R.; Selvaggi, M.; Staykova, Z.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Blekman, F.; Blyweert, S.; D'Hondt, J.; Gonzalez Suarez, R.; Kalogeropoulos, A.; Maes, M.; Olbrechts, A.; Van Doninck, W.; Van Mulders, P.; Van Onsem, G. P.; Villella, I.; Clerbaux, B.; De Lentdecker, G.; Dero, V.; Gay, A. P. R.; Hreus, T.; Léonard, A.; Marage, P. E.; Reis, T.; Thomas, L.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Adler, V.; Beernaert, K.; Cimmino, A.; Costantini, S.; Garcia, G.; Grunewald, M.; Klein, B.; Lellouch, J.; Marinov, A.; Mccartin, J.; Ocampo Rios, A. A.; Ryckbosch, D.; Strobbe, N.; Thyssen, F.; Tytgat, M.; Verwilligen, P.; Walsh, S.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Bruno, G.; Castello, R.; Ceard, L.; Delaere, C.; du Pree, T.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Lemaitre, V.; Liao, J.; Militaru, O.; Nuttens, C.; Pagano, D.; Pin, A.; Piotrzkowski, K.; Schul, N.; Vizan Garcia, J. M.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Alves, G. A.; Correa Martins Junior, M.; De Jesus Damiao, D.; Martins, T.; Pol, M. E.; Souza, M. H. G.; Aldá Júnior, W. L.; Carvalho, W.; Custódio, A.; Da Costa, E. M.; De Oliveira Martins, C.; Fonseca De Souza, S.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Oguri, V.; Prado Da Silva, W. L.; Santoro, A.; Soares Jorge, L.; Sznajder, A.; Bernardes, C. A.; Dias, F. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Lagana, C.; Marinho, F.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Genchev, V.; Iaydjiev, P.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Tcholakov, V.; Trayanov, R.; Vutova, M.; Dimitrov, A.; Hadjiiska, R.; Kozhuharov, V.; Litov, L.; Pavlov, B.; Petkov, P.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Jiang, C. H.; Liang, D.; Liang, S.; Meng, X.; Tao, J.; Wang, J.; Wang, X.; Wang, Z.; Xiao, H.; Xu, M.; Zang, J.; Zhang, Z.; Asawatangtrakuldee, C.; Ban, Y.; Guo, S.; Guo, Y.; Li, W.; Liu, S.; Mao, Y.; Qian, S. J.; Teng, H.; Wang, S.; Zhu, B.; Zou, W.; Avila, C.; Gomez, J. P.; Gomez Moreno, B.; Osorio Oliveros, A. F.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Plestina, R.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Duric, S.; Kadija, K.; Luetic, J.; Morovic, S.; Attikis, A.; Galanti, M.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Finger, M.; Finger, M., Jr.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Khalil, S.; Mahmoud, M. A.; Radi, A.; Kadastik, M.; Müntel, M.; Raidal, M.; Rebane, L.; Tiko, A.; Azzolini, V.; Eerola, P.; Fedi, G.; Voutilainen, M.; Härkönen, J.; Heikkinen, A.; Karimäki, V.; Kinnunen, R.; Kortelainen, M. J.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Ungaro, D.; Wendland, L.; Banzuzi, K.; Karjalainen, A.; Korpela, A.; Tuuva, T.; Besancon, M.; Choudhury, S.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Malcles, J.; Millischer, L.; Nayak, A.; Rander, J.; Rosowsky, A.; Shreyber, I.; Titov, M.; Baffioni, S.; Beaudette, F.; Benhabib, L.; Bianchini, L.; Bluj, M.; Broutin, C.; Busson, P.; Charlot, C.; Daci, N.; Dahms, T.; Dobrzynski, L.; Granier de Cassagnac, R.; Haguenauer, M.; Miné, P.; Mironov, C.; Nguyen, M.; Ochando, C.; Paganini, P.; Sabes, D.; Salerno, R.; Sirois, Y.; Veelken, C.; Zabi, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bodin, D.; Brom, J.-M.; Cardaci, M.; Chabert, E. C.; Collard, C.; Conte, E.; Drouhin, F.; Ferro, C.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Juillot, P.; Le Bihan, A.-C.; Van Hove, P.; Fassi, F.; Mercier, D.; Beauceron, S.; Beaupere, N.; Bondu, O.; Boudoul, G.; Chasserat, J.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Kurca, T.; Lethuillier, M.; Mirabito, L.; Perries, S.; Sordini, V.; Tosi, S.; Tschudi, Y.; Verdier, P.; Viret, S.; Tsamalaidze, Z.; Anagnostou, G.; Beranek, S.; Edelhoff, M.; Feld, L.; Heracleous, N.; Hindrichs, O.; Jussen, R.; Klein, K.; Merz, J.; Ostapchuk, A.; Perieanu, A.; Raupach, F.; Sammet, J.

    2012-10-01

    The transverse energy (ET) in Pb-Pb collisions at 2.76 TeV nucleon-nucleon center-of-mass energy (sNN) has been measured over a broad range of pseudorapidity (η) and collision centrality by using the CMS detector at the LHC. The transverse energy density per unit pseudorapidity (dET/dη) increases faster with collision energy than the charged particle multiplicity. This implies that the mean energy per particle is increasing with collision energy. At all pseudorapidities, the transverse energy per participating nucleon increases with the centrality of the collision. The ratio of transverse energy per unit pseudorapidity in peripheral to central collisions varies significantly as the pseudorapidity increases from η=0 to |η|=5.0. For the 5% most central collisions, the energy density per unit volume is estimated to be about 14GeV/fm3 at a time of 1fm/c after the collision. This is about 100 times larger than normal nuclear matter density and a factor of 2.6 times higher than the energy density reported at sNN=200GeV at the Relativistic Heavy Ion Collider.

  4. Measurement of the pseudorapidity and centrality dependence of the transverse energy density in Pb-Pb collisions at √(s(NN))=2.76 TeV.

    Science.gov (United States)

    Chatrchyan, S; Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hörmann, N; Hrubec, J; Jeitler, M; Kiesenhofer, W; Knünz, V; Krammer, M; Liko, D; Mikulec, I; Pernicka, M; Rahbaran, B; Rohringer, C; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Bansal, S; Cornelis, T; De Wolf, E A; Janssen, X; Luyckx, S; Maes, T; Mucibello, L; Ochesanu, S; Roland, B; Rougny, R; Selvaggi, M; Staykova, Z; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Van Spilbeeck, A; Blekman, F; Blyweert, S; D'Hondt, J; Gonzalez Suarez, R; Kalogeropoulos, A; Maes, M; Olbrechts, A; Van Doninck, W; Van Mulders, P; Van Onsem, G P; Villella, I; Clerbaux, B; De Lentdecker, G; Dero, V; Gay, A P R; Hreus, T; Léonard, A; Marage, P E; Reis, T; Thomas, L; Vander Velde, C; Vanlaer, P; Wang, J; Adler, V; Beernaert, K; Cimmino, A; Costantini, S; Garcia, G; Grunewald, M; Klein, B; Lellouch, J; Marinov, A; Mccartin, J; Ocampo Rios, A A; Ryckbosch, D; Strobbe, N; Thyssen, F; Tytgat, M; Verwilligen, P; Walsh, S; Yazgan, E; Zaganidis, N; Basegmez, S; Bruno, G; Castello, R; Ceard, L; Delaere, C; du Pree, T; Favart, D; Forthomme, L; Giammanco, A; Hollar, J; Lemaitre, V; Liao, J; Militaru, O; Nuttens, C; Pagano, D; Pin, A; Piotrzkowski, K; Schul, N; Vizan Garcia, J M; Beliy, N; Caebergs, T; Daubie, E; Hammad, G H; Alves, G A; Correa Martins Junior, M; De Jesus Damiao, D; Martins, T; Pol, M E; Souza, M H G; Aldá Júnior, W L; Carvalho, W; Custódio, A; Da Costa, E M; De Oliveira Martins, C; Fonseca De Souza, S; Matos Figueiredo, D; Mundim, L; Nogima, H; Oguri, V; Prado Da Silva, W L; Santoro, A; Soares Jorge, L; Sznajder, A; Bernardes, C A; Dias, F A; Fernandez Perez Tomei, T R; Gregores, E M; Lagana, C; Marinho, F; Mercadante, P G; Novaes, S F; Padula, Sandra S; Genchev, V; Iaydjiev, P; Piperov, S; Rodozov, M; Stoykova, S; Sultanov, G; Tcholakov, V; Trayanov, R; Vutova, M; Dimitrov, A; Hadjiiska, R; Kozhuharov, V; Litov, L; Pavlov, B; Petkov, P; Bian, J G; Chen, G M; Chen, H S; Jiang, C H; Liang, D; Liang, S; Meng, X; Tao, J; Wang, J; Wang, X; Wang, Z; Xiao, H; Xu, M; Zang, J; Zhang, Z; Asawatangtrakuldee, C; Ban, Y; Guo, S; Guo, Y; Li, W; Liu, S; Mao, Y; Qian, S J; Teng, H; Wang, S; Zhu, B; Zou, W; Avila, C; Gomez, J P; Gomez Moreno, B; Osorio Oliveros, A F; Sanabria, J C; Godinovic, N; Lelas, D; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Kovac, M; Brigljevic, V; Duric, S; Kadija, K; Luetic, J; Morovic, S; Attikis, A; Galanti, M; Mavromanolakis, G; Mousa, J; Nicolaou, C; Ptochos, F; Razis, P A; Finger, M; Finger, M; Assran, Y; Elgammal, S; Ellithi Kamel, A; Khalil, S; Mahmoud, M A; Radi, A; Kadastik, M; Müntel, M; Raidal, M; Rebane, L; Tiko, A; Azzolini, V; Eerola, P; Fedi, G; Voutilainen, M; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Peltola, T; Tuominen, E; Tuominiemi, J; Tuovinen, E; Ungaro, D; Wendland, L; Banzuzi, K; Karjalainen, A; Korpela, A; Tuuva, T; Besancon, M; Choudhury, S; Dejardin, M; Denegri, D; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Locci, E; Malcles, J; Millischer, L; Nayak, A; Rander, J; Rosowsky, A; Shreyber, I; Titov, M; Baffioni, S; Beaudette, F; Benhabib, L; Bianchini, L; Bluj, M; Broutin, C; Busson, P; Charlot, C; Daci, N; Dahms, T; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Mironov, C; Nguyen, M; Ochando, C; Paganini, P; Sabes, D; Salerno, R; Sirois, Y; Veelken, C; Zabi, A; Agram, J-L; Andrea, J; Bloch, D; Bodin, D; Brom, J-M; Cardaci, M; Chabert, E C; Collard, C; Conte, E; Drouhin, F; Ferro, C; Fontaine, J-C; Gelé, D; Goerlach, U; Juillot, P; Le Bihan, A-C; Van Hove, P; Fassi, F; Mercier, D; Beauceron, S; Beaupere, N; Bondu, O; Boudoul, G; Chasserat, J; Chierici, R; Contardo, D; Depasse, P; El Mamouni, H; Fay, J; Gascon, S; Gouzevitch, M; Ille, B; Kurca, T; Lethuillier, M; Mirabito, L; Perries, S; Sordini, V; Tosi, S; Tschudi, Y; Verdier, P; Viret, S; Tsamalaidze, Z; Anagnostou, G; Beranek, S; Edelhoff, M; Feld, L; Heracleous, N; Hindrichs, O; Jussen, R; Klein, K; Merz, J; Ostapchuk, A; Perieanu, A; Raupach, F; Sammet, J; Schael, S; Sprenger, D; Weber, H; Wittmer, B; Zhukov, V; Ata, M; Caudron, J; Dietz-Laursonn, E; Erdmann, M; Güth, A; Hebbeker, T; Heidemann, C; Hoepfner, K; Klingebiel, D; Kreuzer, P; Lingemann, J; Magass, C; Merschmeyer, M; Meyer, A; Olschewski, M; Papacz, P; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Steggemann, J; Teyssier, D; Weber, M; Bontenackels, M; Cherepanov, V; Flügge, G; Geenen, H; Geisler, M; Haj Ahmad, W; Hoehle, F; Kargoll, B; Kress, T

    2012-10-12

    The transverse energy (E(T)) in Pb-Pb collisions at 2.76 TeV nucleon-nucleon center-of-mass energy (√(s(NN)) has been measured over a broad range of pseudorapidity (η) and collision centrality by using the CMS detector at the LHC. The transverse energy density per unit pseudorapidity (dE(T)/dη) increases faster with collision energy than the charged particle multiplicity. This implies that the mean energy per particle is increasing with collision energy. At all pseudorapidities, the transverse energy per participating nucleon increases with the centrality of the collision. The ratio of transverse energy per unit pseudorapidity in peripheral to central collisions varies significantly as the pseudorapidity increases from η=0 to |η|=5.0. For the 5% most central collisions, the energy density per unit volume is estimated to be about 14 GeV/fm(3) at a time of 1 fm/c after the collision. This is about 100 times larger than normal nuclear matter density and a factor of 2.6 times higher than the energy density reported at √(s(NN))=200 GeV at the Relativistic Heavy Ion Collider.

  5. Appropriate choice of collision-induced dissociation energy for qualitative analysis of notoginsenosides based on liquid chromatography hybrid ion trap time-of-flight mass spectrometry.

    Science.gov (United States)

    Wang, Guang-Ji; Fu, Han-Xu; Xiao, Jing-Cheng; Ye, Wei; Rao, Tai; Shao, Yu-Hao; Kang, Dian; Xie, Lin; Liang, Yan

    2016-04-01

    Liquid chromatography hybrid ion trap/time-of-flight mass spectrometry possessesd both the MS(n) ability of ion trap and the excellent resolution of a time-of-flight, and has been widely used to identify drug metabolites and determine trace multi-components for in natural products. Collision energy, one of the most important factors in acquiring MS(n) information, could be set freely in the range of 10%-400%. Herein, notoginsenosides were chosen as model compounds to build a novel methodology for the collision energy optimization. Firstly, the fragmental patterns of the representatives for the authentic standards of protopanaxadiol-type and protopanaxatriol-type notoginsenosides authentic standards were obtained based on accurate MS(2) and MS(3) measurements via liquid chromatography hybrid ion trap/time-of-flight mass spectrometry. Then the extracted ion chromatograms of characteristic product ions of notoginsenosides in Panax Notoginseng Extract, which were produced under a series of collision energies and, were compared to screen out the optimum collision energies values for MS(2) and MS(3). The results demonstrated that the qualitative capability of liquid chromatography hybrid ion trap/time-of-flight mass spectrometry was greatly influenced by collision energies, and 50% of MS(2) collision energy was found to produce the highest collision-induced dissociation efficiency for notoginsenosides. BesidesAddtionally, the highest collision-induced dissociation efficiency appeared when the collision energy was set at 75% in the MS(3) stage.

  6. Experimental study of collective flow phenomena in high-energy nucleus-nucleus collisions

    CERN Document Server

    Chkhaidze, L V; Kharkhelauri, L L

    2002-01-01

    The results of the experimental study of collective flow phenomena, such as the sideward and elliptic flow of nuclear matter, discovered during the last 10-15 years in high-energy nucleus-nucleus collisions are presented in this review. Sideward (often termed directed) and elliptic flows have been observed for protons, antiprotons, light nuclei, pions, kaons, and lambdas emitted in nucleus-nucleus collisions at 0.1-1.8 GeV/nucleon of LBL Bevalac and GSI/SIS by Plastic-Ball, Streamer Chamber, EOS-NPC, FOPI, LAND, TAPS, and KAOS collaborations; at 2-4 GeV/nucleon of Dubna JINR by SKM-200-GIBS, Propane Buble Chamber, and Emulsion Chamber collaborations; at 2-14 GeV/nucleon of BNL AGS, by the E877, E895, and E917 collaborations; and at 60 and 200 GeV/nucleon of CERN SPS, by the WA98 and NA49 collaborations and more recently by the STAR at RHIC BNL. In the review, the results of the SKM-200-GIBS collaboration of JINR are presented and compared with the results of different experiments by Bevalac, GSI/SIS, BNL, and...

  7. Parton cascade description of relativistic heavy-ion collisions at CERN SPS energies?

    CERN Document Server

    Kinder-Geiger, Klaus; Geiger, Klaus; Srivastava, Dinesh Kumar

    1997-01-01

    We examine Pb+Pb collisions at CERN SPS energy 158 A GeV, by employing the earlier developed and recently refined parton-cascade/cluster-hadronization model and its Monte Carlo implementation. This space-time model involves the dynamical interplay of perturbative QCD parton production and evolution, with non-perturbative parton-cluster formation and hadron production through cluster decays. Using computer simulations, we are able to follow the entwined time-evolution of parton and hadron degrees of freedom in both position and momentum space, from the instant of nuclear overlap to the final yield of particles. We present and discuss results for the multiplicity distributions, which agree well with the measured data from the CERN SPS, including those for K mesons. The transverse momentum distributions of the produced hadrons are also found to be in good agreement with the preliminary data measured by the NA49 and the WA98 collaboration for the collision of lead nuclei at the CERN SPS. The analysis of the time ...

  8. Quantum dynamics of the charge transfer in C{sup +} + S at low collision energies

    Energy Technology Data Exchange (ETDEWEB)

    Chenel, Aurelie; Mangaud, Etienne; Justum, Yves; Desouter-Lecomte, Michele [Laboratoire de Chimie Physique, Bat 349, Univ-ParisSud et CNRS-UMR8000, F-91405 Orsay Cedex (France); Talbi, Dahbia [Groupe de Recherche en Astronomie et Astrophysique du Languedoc, Universite de Montpellier II et CNRS-UMR5024, Place Eugene Bataillon, F-34095 Montpellier Cedex 05 (France); Bacchus-Montabonel, Marie-Christine, E-mail: michele.desouter-lecomte@u-psud.f [Laboratoire de Spectrometrie Ionique et moleculaire, Universite de Lyon I et CNRS-UMR5579, 43 Bd du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

    2010-12-28

    Following a recent semiclassical investigation by Bacchus-Montabonel and Talbi (2008 Chem. Phys. Lett. 467 28), the C{sup +}(2s{sup 2}2p){sup 2}P + S(3s{sup 2}3p{sup 4}){sup 3}P charge transfer process involved in the modellization of the interstellar medium chemistry and its reverse reaction are revisited by combining a wave packet approach and semiclassical dynamics in a quasimolecular approach for doublet and quartet states. New radial non-adiabatic coupling matrix elements have been calculated and the mixed treatment gives access to new precise values of the rate coefficients for the direct and reverse charge transfer processes. For this system, quantum and semiclassical results are in good agreement even at low collision kinetic energies. The dominance of the quartet states in the process is confirmed. In the quantum treatment, the collision matrix elements are extracted from wave packets by the flux method with an absorbing potential. The formation of resonances due to a centrifugal barrier is illustrated.

  9. Production of Forward Rapidity Photons in High Energy Heavy Ion Collisions

    CERN Document Server

    Jalilian-Marian, J

    2005-01-01

    We consider production of prompt photons in high energy gold-gold and deuteron-gold collisions in the forward rapidity region of RHIC ($y \\sim 3.8$). In this kinematics, the projectile partons typically have large $x_{bj}$ while the target partons are mostly at very small $x_{bj}$ so that the primary partonic collisions involve valence quarks from the projectile and gluons from the target. We take the target nucleus to be a Color Glass Condensate while the projectile deuteron or nucleus is treated as a dilute system of partons. We show that the photon production cross section can be written as a convolution of a quark-nucleus scattering cross section, involving a quark anti-quark dipole, with the Leading Order quark-photon fragmentation function. We consider different models of the quark anti-quark dipole and show that measurement of photons in the forward rapidity region at RHIC can distinguish between different parameterizations of the dipole cross section as well as help clarify the role of parton coalesce...

  10. Heavy-flavour production in high-energy d-Au and p-Pb collisions

    CERN Document Server

    Beraudo, Andrea; Monteno, Marco; Nardi, Marzia; Prino, Francesco

    2015-01-01

    Soft-hadron measurements in high-energy collisions of small systems like p-Pb and d-Au show peculiar qualitative features (long-range rapidity correlations, flattening of the $p_T$-spectra with increasing hadron mass and centrality, non-vanishing Fourier harmonics in the azimuthal particle distributions) suggestive of the formation of a strongly-interacting medium displaying a collective behaviour, with a hydrodynamic flow as a response to the pressure gradients in the initial conditions. Hard observables (high-$p_T$ jet and hadron spectra) on the other hand, within the current large systematic uncertainties, appear only midly modified with the respect to the benchmark case of minimum-bias p-p collisions. What should one expect for heavy-flavour particles, initially produced in hard processes but tending, in the nucleus-nucleus case, to approach kinetic equilibrium with the rest of the medium? This is the issue we address in the present study, showing how the current experimental findings are compatible with ...

  11. Isospin Effect of Coulomb Interaction on Momentum Dissipation in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Ye; GUO Wen-Jun; XING Yong-Zhong; Li Xi-Guo

    2004-01-01

    We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section.In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential.

  12. Atomic data on inelastic processes in low-energy beryllium-hydrogen collisions

    Science.gov (United States)

    Yakovleva, Svetlana A.; Voronov, Yaroslav V.; Belyaev, Andrey K.

    2016-08-01

    Aims: Inelastic processes in low-energy Be + H and Be+ + H- collisions are treated for the states from the ground and up to the ionic state with the aim to provide rate coefficients needed for non-local thermodynamic equilibrium (non-LTE) modeling of beryllium spectra in cool stellar atmospheres. Methods: The electronic molecular structure is determined by using a recently proposed model quantum approach that is based on an asymptotic method. Nonadiabatic nuclear dynamics is treated by means of multichannel formulas, based on the Landau-Zener model for nonadiabatic transition probabilities. Results: The cross sections and the rate coefficients for inelastic processes in Be + H and Be+ + H- collisions are calculated for all transitions between 13 low-lying covalent states plus the ionic state. It is shown that the highest rate coefficient values correspond to the mutual neutralization processes with the final states Be(2s3s 1S), Be(2s3p 1,3P), Be(2s3d 3D). These processes, as well as some of the excitation, de-excitation and ion-pair formation processes, are likely to be important for non-LTE modeling. Tables A.1-A.10 are also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A27

  13. Measurements of electron detachment cross sections in 10-50 keV impact energy H{sup {minus}} + collisions

    Energy Technology Data Exchange (ETDEWEB)

    Seely, D.G. [Albion College, MI (United States); Sen, A.; Kvale, T.J. [Univ. of Toledo, OH (United States)

    1996-05-01

    Absolute cross sections for the single- and double-electron detachment ({sigma}{sub {minus}10} and {sigma}{sub {minus}11}, respectively) in collisions between H{sup {minus}} and methane have been measured in the energy range of 10-50 keV. A well-collimated H{sup {minus}} ion beam was accelerated into a gas target cell containing methane and the scattered H{sup {minus},0,+} beam components of the collision products were magnetically separated and simultaneously measured by separate detectors. The cross sections were determined by quadratic least squares fits of the scattered-beam growth curves. In the present energy region, {sigma}{sub {minus}10} exhibits a maximum at around 20 keV impact energy and then monotonically decreases with increasing impact energy. However, {sigma}{sub {minus}11} displays a different energy dependence by monotonically increasing with increasing impact energy until about 25 keV and thereafter remaining relatively constant.

  14. Dynamical effects and fission in the heavy ion collisions at incident energies near the Fermi energy; Effets dynamiques et fission dans les collisions d`ions lourds a des energies incidentes voisines de l`energie de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    Jean Colin [Lab. de Physique Corpusculaire, Caen Univ., 14 (France)

    1997-12-01

    In this work we have studied the reaction mechanisms implied in the heavy ion collisions at energies near the Fermi level. We have observed the predominance of binary processes (2 principal nuclei in the exit channel) and selected events leading to the fission of one of the two fragmentation products. On the basis of the study of angular distributions of fission fragments and associated light particles, we have determined the angular momentum of the nucleus in the moment of fission and the angular momentum transfer in the interaction. The comparison of experimental values of the angular momentum transferred with the theoretical models enables the characterization of projectile-target interaction. For the different systems studied, the spin of fissioning nucleus ranges between 30 {Dirac_h} and 60 {Dirac_h} while the transferred angular momentum may reach 90 {Dirac_h}. For these studies the determinant parameter is the sequence of emission of light particles and fragments, hence the lifetime associated to each processes. For central collisions we have measured pre-fission lifetimes lower then 10{sup -21} sec. These values are very short in comparison with the statistical fission processes, what prompted to search for off-equilibrium (non-statistical) phenomena in the data. Taking into account the charges of the fission fragments we were able to isolate a dynamical component and a statistical component in the fission process. We have compared these two classes of events and showed that there is a relative excess of energy between the fragments when the origin of scission is dynamical. We hope to derive of this observable the nuclear deformation velocity and constrain the value of the nuclear matter viscosity in comparison with the theoretical models 54 refs., 27 figs., 2 tabs.

  15. Transverse momentum spectra in high-energy nucleus-nucleus, proton-nucleus and proton-proton collisions

    Institute of Scientific and Technical Information of China (English)

    XIE Wen-Jie

    2011-01-01

    The transverse momentum distributions of final-state particles produced in nucleus-nucleus (AA),proton-nucleus (pA),and proton-proton (pp) collisions at high energies are investigated using a multisource ideal gas model.Our calculated results show that the contribution of hard emission can be neglected in the study of transverse momentum spectra of charged pions and kaons produced in Cu-Cu collisions at (√SNN)=22.5 GeV.And if we consider the contribution of hard emission,the transverse momentum spectra of p and (P) produced in Cu-Cu collisions at (√SNN)=22.5 GeV,KsO produced in Pb-Pb collisions at 158 A GeV,J/ψ particles produced in p-Pb collisions at 400 GeV and π+,K+,p produced in proton-proton collisions at (√S)=200 GeV,can be described by the model,especially in the tail part of spectra.

  16. Emission of fragments in heavy ion-collisions at Fermi energy; Modes de production des fragments dans les collisions d'ions lourds aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Normand, J

    2001-10-01

    The study of reaction mechanisms in Fermi energy domain has shown the dominant binary character of the process. The two heavy sources produced after the first stage of the interaction (the quasi-projectile QP and the quasi-target QT) can experience various decay modes from evaporation to multifragmentation. However, the presence of light fragments at mid rapidity cannot be explained by the standard decay of the QP and the QT. To understand the mechanisms producing such a contribution, the break-up of the QP has been studied on the following systems: Xe+Sn from 25 to 50 MeV/A, Ta+Au and Ta+U at 33, 39.6 MeV/A and U+U at 24 MeV/A. The experiment has been performed at GANIL with the INDRA multidetector. The particular behaviour of the heaviest fragment and the correlation between the charge and the velocity of the fragments suggest a shape deformation followed by the rupture of a neck formed in between the two partners of the collision. The heaviest fragment could be the reminiscence of the projectile. A method based on the angular distribution of the heaviest fragment has allowed to separate the statistical break-up of the QP and the non equilibrated break-up. The statistical break-up ranges from 30 % to 75 % of the break-ups. The comparison of the statistical component with a statistical model gives information about the charge, the angular momentum and the temperature of the QP. The comparison of the non equilibrated component with dynamical models could give information about the parameters of the nuclear interaction in medium. (author)

  17. Influence of collision energy on cross section and stereodynamical properties for the reaction H + OCl {yields} OH + Cl

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Shengwen [School of Physics and Optoelectronic Engineering, Dalian University of Technology, Dalian 116021 (China); Wang Yunhui [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China); Lu Ruifeng, E-mail: rflu@mail.njust.edu.cn [Department of Applied Physics, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2012-06-19

    Graphical abstract: Display Omitted Highlights: Black-Right-Pointing-Pointer The first QCT investigation for the reaction H + OCl {yields} OH + Cl. Black-Right-Pointing-Pointer The influence of collision energy on scalar properties including reaction probability and the integral cross-section. Black-Right-Pointing-Pointer Full information about stereodynamics of product alignment and orientation. - Abstract: The quasi-classical trajectory calculations are carried out for the reaction H + OCl {yields} OH + Cl on the singlet ground state potential energy surface. The reaction probability for total angular momentum J = 0 and the integral cross section as a function of collision energy are presented. Furthermore, the product rotational alignment has been obtained, and the value tends to decrease with the increasing of collision energy with fluctuations. To investigate the collision-energy-dependent effects on chemical stereodynamics, the four generalized polarization-dependent differential cross sections (2{pi}/{sigma})(d{sigma}{sub 00}/d{omega}{sub t}), (2{pi}/{sigma})(d{sigma}{sub 20}/d{omega}{sub t}), (2{pi}/{sigma})(d{sigma}{sub 22+}/d{omega}{sub t}) and (2{pi}/{sigma})(d{sigma}{sub 21-}/d{omega}{sub t}), the distribution P({theta}{sub r}) of the angle between j Prime -k and the angle distribution P({phi}{sub r}) in terms of k-k Prime -j Prime correlation have also been calculated.

  18. Energy and target dependence of the pseudo-rapidity distributions in pion- and proton-nucleus collisions at Fermilab energies

    Energy Technology Data Exchange (ETDEWEB)

    Busza, W.; Luckey, D.; Votta, L.; Young, C.; Halliwell, C.; Elias, J.

    1976-01-01

    Multiparticle production in hadron-nucleus collisions has been studied using hodoscope arrays. Data on angular distributions were collected for incident ..pi../sup + -/, K/sup + -/, and P/sup + -/ at 50, 100, and 200 GeV with targets ranging from hydrogen through uranium. The extent in pseudo-rapidity of particles produced in the target fragmentation region increases with energy. Proton and pion induced reactions exhibit different behavior for the same target nucleus. However, for target nuclei with identical values of ..nu..bar, (where ..nu..bar is the average thickness in units of the mean free path of the incident particle) the behavior is similar. Pseudo-rapidity distributions are compared with theoretical models.

  19. Isospin Effect on Nuclear Stopping in Intermediate Energy Heavy Ion Collisions

    Institute of Scientific and Technical Information of China (English)

    李庆峰; 李祝霞

    2002-01-01

    By using the isospin-dependent quantum molecular dynamics model, we study the dependence of nuclear stopping Qzz/A and R in intermediate energy heavy ion collisions on system size, initial N/Z, isospin symmetry potential and the medium correction of two-body cross sections. We find the effect of the initial N/Z ratio and isospinsymmetry potential on stopping is weak. The excitation function of Qzz/A and R depends on the form of medium correction of two-body cross sections, the equation ofstate of nuclear matter. Our results show that the behaviour of the excitation function of Qzz/A and R can provide clearer information of the isospin dependence of the medium correction of two-body cross sections

  20. Energy and centrality dependences of charged multiplicity pseudorapidity density in relativistic nuclear collisions

    CERN Document Server

    Zhou Dai Mei; Sá Ben-Hao; Li Zhong Dao

    2002-01-01

    Using a hadron and string cascade model, JPCIAE, and the corresponding Monte Carlo events generator, the energy and centrality dependences of charged particle pseudorapidity density in relativistic nuclear collisions were studied. Within the framework of this model, both the relativistic p anti p experimental data and the PHOBOS and PHENIX Au + Au data could be reproduced fairly well without retuning the model parameters. The author shows that since is not a well defined physical variable both experimentally and theoretically, the charged particle pseudorapidity density per participant pair can increase and also can decrease with increasing of , so it may be hard to use charged particle pseudorapidity density per participant pair as a function of to distinguish various theoretical models for particle production

  1. Chiral symmetry restoration in heavy-ion collisions at intermediate energies

    CERN Document Server

    Palmese, A; Seifert, E; Steinert, T; Moreau, P; Bratkovskaya, E L

    2016-01-01

    We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range $\\sqrt{s_{NN}}$=3-20 GeV within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear $\\sigma-\\omega$ model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations.

  2. Longitudinal phase space of multiparticle final states in high energy hadron-hadron collisions

    Institute of Scientific and Technical Information of China (English)

    吴元芳; 刘连寿

    1995-01-01

    The highly anisotropic phase space (known as longitudinal phase space) of multipartide final states in high energy hh collisions is studied in detail. It is pointed out that the anisotropy of phase space should manifest itself not only in the dramatic difference in magnitude between the average transverse and longitudinal momenta, but also in the anisotropy of dynamical fluctuations in the two directions. It means that the particle distribution in phase space has the property of selfaffine fractal. A method for experimentally testing the selfaffine fractality and measuring its cbaracteristic parameterHurst exponent is given. In addition, the correlation between the degree of longitudinal fractality and the magnitude of average transverse momentum is discussed. A new characteristic quantity--average transverse momentum per event--for de scribing the dynamical property of an event (hard, soft or ultrasoft) is proposed. A comparison of the results with experimental data is given.

  3. Oscillations of moments in high-energy nucleus-nucleus collisions

    Institute of Scientific and Technical Information of China (English)

    杨红艳; 周代翠; 钱琬燕; 王晓荣

    2001-01-01

    The definitions of density function and moment of multiplicity distribution are introduced,and the method of moment analysis in e+ e- and proton-proton (pp) interactions is extended into nu-cleus-nucleus (AA) interactions. We analyze the data for relativistic nucleus-nucleus collisions and cal-culate the values of Hq for charged particle multiplicity distributions, by which we study systematically the dependences of Hq on incident energy, mass of colliding system, pseudorapidity interval, centrality and truncation of multiplicity. We compare the oscillation structures induced by e + e-, pp and AA inter-actions, and the comparison and analysis are carried out between experimental data and QCD predic-tion. The latest results are given in this paper.

  4. Heavy-flavor production and medium properties in high-energy nuclear collisions. What next?

    Energy Technology Data Exchange (ETDEWEB)

    Aarts, G.; Allton, C. [Swansea University, Swansea (United Kingdom); Aichelin, J.; Gossiaux, P.B.; Nahrgang, M. [Universite de Nantes, SUBATECH, Ecole des Mines de Nantes, Nantes (France); Arnaldi, R.; Scomparin, E. [INFN, Sezione di Torino, Torino (Italy); Bass, S.A. [Duke University, Durham, NC (United States); Bedda, C.; Grelli, A.; Trzeciak, B.; Doremalen, L. van; Vermunt, L.; Vigolo, S. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); Brambilla, N. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Technische Universitaet Muenchen, Institute for Advanced Study, Munich (Germany); Bratkovskaya, E. [GSI Helmholtzzentrum fuer Schwerionenforschung, Research Division and ExtreMe Matter Institute EMMI, Darmstadt (Germany); Frankfurt University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Braun-Munzinger, P. [GSI Helmholtzzentrum fuer Schwerionenforschung, Research Division and ExtreMe Matter Institute EMMI, Darmstadt (Germany); Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Bruno, G.E. [Dipartimento di Fisica and INFN, Bari (Italy); European Organization for Nuclear Research, Geneva (Switzerland); Dahms, T. [Technische Universitaet Muenchen, Physik-Department and Excellence Cluster Universe, Garching (Germany); Das, S.K. [University of Catania, Catania (Italy); Dembinski, H.; Schmelling, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Djordjevic, M. [University of Belgrade, Institute of Physics, Belgrade (Serbia); Ferreiro, E. [Universidad de Santiago de Compostela, Santiago de Compostela (Spain); Frawley, A. [Florida State University, Tallahassee, FL (United States); Granier de Cassagnac, R.; Jo, M.; Nguyen, M. [Ecole Polytechnique, Laboratoire Leprince-Ringuet, Palaiseau (France); He, M. [Nanjing University of Science and Technology, Department of Applied Physics, Nanjing (China); Horowitz, W.A. [University of Cape Town, Department of Physics, Rondebosch (South Africa); Innocenti, G.M. [Massachusetts Institute of Technology, Cambridge, MA (United States); Kaczmarek, O. [Key Laboratory of Quark and Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University, Wuhan (China); University of Bielefeld, Bielefeld (Germany); Kuijer, P.G. [National Institute for Subatomic Physics, Amsterdam (Netherlands); Laine, M. [University of Bern, AEC, Institute for Theoretical Physics, Bern (Switzerland); Lombardo, M.P. [INFN - Laboratori Nazionali di Frascati, Frascati (Italy); Mischke, A. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); National Institute for Subatomic Physics, Amsterdam (Netherlands); Munhoz, M.G.; Suaide, A.A.P. [Universidade de Sao Paulo (USP), Sao Paulo (Brazil); Oliveira da Silva, A.C.; Zanoli, H.J.C. [Utrecht University, Institute for Subatomic Physics, Utrecht (Netherlands); Universidade de Sao Paulo (USP), Sao Paulo (Brazil); Petreczky, P. [Brookhaven National Laboratory, Upton, NY (United States); Rothkopf, A. [Ruprecht-Karls-Universitaet Heidelberg, Institute for Theoretical Physics, Heidelberg (Germany); Song, T. [Frankfurt University, Institute for Theoretical Physics, Frankfurt am Main (Germany); Stachel, J. [Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Tolos, L. [Frankfurt Institute for Advanced Studies (FIAS), Frankfurt (Germany); Institut de Ciencies de l' Espai (IEEC-CSIC), Bellaterra (Spain); Uras, A. [Domaine Scientifique de la Doua, Institute of Nuclear Physics, Villeurbanne Cedex (France); Xu, N. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Ye, Z. [University of Illinois, Chicago, IL (United States); Zhuang, P. [Tsinghua University, Beijng Shi (China)

    2017-05-15

    Open and hidden heavy-flavor physics in high-energy nuclear collisions are entering a new and exciting stage towards reaching a clearer understanding of the new experimental results with the possibility to link them directly to the advancement in lattice Quantum Chromo-Dynamics (QCD). Recent results from experiments and theoretical developments regarding open and hidden heavy-flavor dynamics have been debated at the Lorentz Workshop Tomography of the Quark-Gluon Plasma with Heavy Quarks, which was held in October 2016 in Leiden, The Netherlands. In this contribution, we summarize identified common understandings and developed strategies for the upcoming five years, which aim at achieving a profound knowledge of the dynamical properties of the quark-gluon plasma. (orig.)

  5. Model investigation of non-thermal phase transition in high energy collisions

    Institute of Scientific and Technical Information of China (English)

    王琴; 李治明; 刘连寿

    2000-01-01

    The non-thermal phase transition in high energy collisions is studied in detail in the frame-work of random cascade model. The relation between the characteristic parameter γq of phase transition and the rank q of moment is obtained using Monte Carlo simulation, and the existence of two phases in self-similar cascading multiparticle systems is shown. The relation between the critical point qc of phase transition on the fluctuation parameter a is obtained and compared with the experimental results from NA22. The same study is carried out also by analytical calculation under central limit ap-proximation. The range of validity of the central limit approximation is discussed.

  6. Anisotropic particle production and azimuthal correlations in high-energy pA collisions

    CERN Document Server

    Dumitru, Adrian; Skokov, Vladimir

    2015-01-01

    We summarize some recent ideas relating to anisotropic particle production in high-energy collisions. Anisotropic gluon distributions lead to anisotropies of the single-particle azimuthal distribution and hence to disconnected contributions to multi-particle cumulants. When these dominate, the four-particle elliptic anisotropy $c_2\\{4\\}$ changes sign. On the other hand, connected diagrams for $m$-particle cumulants are found to quickly saturate with increasing $m$, a ``coherence'' quite unlike conventional ``non-flow'' contributions such as decays. Finally, we perform a first exploratory phenomenological analysis in order to estimate the amplitude ${\\cal A}$ of the $\\cos(2\\varphi)$ anisotropy of the gluon distribution at small $x$, and we provide a qualitative prediction for the elliptic asymmetry from three-particle correlations, $c_2\\{3\\}$.

  7. Searching for Minimum in Dependence of Squared Speed-of-Sound on Collision Energy

    Directory of Open Access Journals (Sweden)

    Fu-Hu Liu

    2016-01-01

    Full Text Available Experimental results of the rapidity distributions of negatively charged pions produced in proton-proton (p-p and beryllium-beryllium (Be-Be collisions at different beam momentums, measured by the NA61/SHINE Collaboration at the super proton synchrotron (SPS, are described by a revised (three-source Landau hydrodynamic model. The squared speed-of-sound parameter cs2 is then extracted from the width of rapidity distribution. There is a local minimum (knee point which indicates a softest point in the equation of state (EoS appearing at about 40A GeV/c (or 8.8 GeV in cs2 excitation function (the dependence of cs2 on incident beam momentum (or center-of-mass energy. This knee point should be related to the searching for the onset of quark deconfinement and the critical point of quark-gluon plasma (QGP phase transition.

  8. High-energy photon collisions at the LHC - dream or reality?

    CERN Document Server

    Klasen, M

    2008-01-01

    We discuss the potential of high-energy photon collisions at the LHC for improving our understanding of QCD and studying the physics beyond the Standard Model. After reviewing briefly the legacy of past photoproduction experiments at LEP and HERA, we examine the gold-plated channels proposed for a photon collider at the ILC for their potential in a hadron collider environment. We stress that initial-state photon interactions have indeed been observed at RHIC and at the Tevatron. Three promising channels at the LHC are then presented in some detail: exclusive vector-meson production, measurements of possibly anomalous electroweak gauge-boson or top-quark couplings, and slepton production.

  9. Hands on CERN an education project on the Internet using real high energy particle collisions

    CERN Document Server

    Johansson, E K

    1999-01-01

    An educational project primarily aimed at teachers and 15 to 18 year- old students describing the essential features of a modern high energy physics experiment has been created. The whole education package is available on the Internet. It gives a detailed description of the physics processes involved and the Standard Model of Microcosm. Real particle collisions produced with the facilities at the European particle physics laboratory (CERN) are displayed using the platform-independent programming language Java, enabling interaction with the user. The project has been used by several groups of teachers and students, and has increased their knowledge of, and interest in, particle physics. This project complements the traditional physics education and introduces students to contemporary fundamental physics. (7 refs).

  10. Recoil ion charge state distributions in low energy Ar{sup q+} {minus} Ar collisions

    Energy Technology Data Exchange (ETDEWEB)

    Vancura, J.; Marchetti, V.; Kostroun, V.O.

    1992-12-31

    We have measured the recoil ion charge state distributions in Ar{sup q+} -- Ar (8{le}q{le}16) collisions at 2.3 qkeV and 0.18qkeV by time of flight (TOF) spectroscopy. For Ar{sup 8-16+}, recoil ion charge states up to 6+ are clearly present, indicating that the 3p subshell in the target atom is being depleted, while for Ar{sup 10-16+}, there is evidence that target 3s electrons are also being removed. Comparison of the recoil ion charge state spectra at 2.3 and 0.18 qkeV shows that for a given projectile charge, there is very little dependence of the observed recoil target charge state distribution on projectile energy.

  11. Fluctuations of Conserved Quantities in High Energy Nuclear Collisions at RHIC

    CERN Document Server

    Luo, Xiaofeng

    2015-01-01

    Fluctuations of conserved quantities in heavy-ion collisions are used to probe the phase transition and the QCD critical point for the strongly interacting hot and dense nuclear matter. The STAR experiment has carried out moment analysis of net-proton (proxy for net-baryon (B)), net-kaon (proxy for net-strangeness (S)), and net-charge (Q). These measurements are important for understanding the quantum chromodynamics phase diagram. We present the analysis techniques used in the moment analysis by the STAR experiment and discuss the moments of net-proton and net-charge distributions from the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider.

  12. Two-pion interferometry in heavy ion collisions at HIRFL-CSR energy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We examine the two-pion Hanbury-Brown-Twiss (HBT) interferometry for the particle-emitting source produced in heavy ion collisions at HIRFL-CSR energy. The source evolution is described by relativistic hydrodynamics with three kinds of equations of state for chemical equilibrium (CE), chemical freeze-out (CFO),and partial chemical equilibrium (PCE) models, respectively. We investigate the effects of particle decay,multiple scattering, and source collective expansion on the two-pion interferometry results. We find that the HBT radii of the evolution source for the CFO and PCE models are smaller than that for the CE model.The HBT lifetime for the CFO model is smaller than those for the PCE and CE models. The particle decay increases the HBT radius and lifetime while the source expansion decreases the HBT radius. The multiple scattering effect on the HBT results can be neglected based on our model calculations.

  13. Departure from equilibrium of the quasiparticle distribution functions in high-energy nuclear collisions

    Science.gov (United States)

    Chakraborty, P.; Kapusta, J. I.

    2017-01-01

    In simulations of high energy heavy ion collisions that employ viscous hydrodynamics, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasiparticle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. We show how distortions of the single particle distribution functions due to both shear and bulk viscous effects can be done rigorously in the quasiparticle approximation and illustrate it with the linear σ model at finite temperature.

  14. Characteristics of Strange Hadron Production in Some High Energy Collisions and The Role of Power Laws

    CERN Document Server

    Biswas, Sunil Kumar; Ghosh, Amar Chandra Das; Bhattacharyya, Subrata; 10.4236/ojm.2012.21001

    2012-01-01

    Studies on `strange' particle production have always occupied a very important space in the domain of Particle Physics. This was and is so, just because of some conjectures about specially abundant or excess production of `strange' particles, at certain stages and under certain conditions arising out of what goes by the name of `Standard' model in Particle Physics. With the help of Hagedornian power laws we have attempted to understand and interpret here the nature of the $p_T$-spectra for the strange particle production in a few high energy nuclear collisions, some interesting ratio-behaviours and the characteristics of the nuclear modification factors that are measured in laboratory experiments. After obtaining and analysing the final results we do not confront any peculiarities or oddities or extraneous excesses in the properties of the relevant observables with no left-over problems or puzzles. The model(s) used by us work(s) quite well for explaining the measured data.

  15. Isospin dependence of collective flow in heavy-ion collisions at intermediate energies

    CERN Document Server

    Li, B A; Ko, C M; Yennello, S J; Li, Bao An

    1996-01-01

    Within the framework of an isospin-dependent Boltzmann-Uehling-Uhlen beck (BUU) model using initial proton and neutron densities calculated from the nonlinear relativistic mean-field (RMF) theory, we compare the strength of transverse collective flow in reactions ^{48}Ca+^{58}Fe and ^{48}Cr+^{58}Ni, which have the same mass number but different neutron/proton ratios. The neutron-rich system (^{48}Ca+^{58}Fe) is found to show significantly stronger negative deflection and consequently has a higher balance energy, especially in peripheral collisions. NOTE ADDED IN PROOF: The new phenomenon predicted in this work has just been confirmed by an experiment done by G.D. Westfall et al. using the NSCL/MSU radioactive beam facility and a spartan soccer. A paper by R. Pak et al. is submitted to PRL to report the experimental result.

  16. Fluctuations of Conserved Quantities in High Energy Nuclear Collisions at RHIC

    Science.gov (United States)

    Luo, Xiaofeng

    2015-04-01

    Fluctuations of conserved quantities in heavy-ion collisions are used to probe the phase transition and the QCD critical point for the strongly interacting hot and dense nuclear matter. The STAR experiment has carried out moment analysis of net-proton (proxy for net- baryon (B)), net-kaon (proxy for net-strangeness (S)), and net-charge (Q). These measurements are important for understanding the quantum chromodynamics phase diagram. We present the analysis techniques used in the moment analysis by the STAR experiment and discuss the moments of net-proton and net-charge distributions from the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider.

  17. Parameterization of the energy and rapidity distributions of secondary pions and kaons produced in energetic proton-proton collisions

    CERN Document Server

    Koers, H B J; Wijers, R A M J; Koers, Hylke B. J.; Pe'er, Asaf; Wijers, Ralph A. M. J.

    2006-01-01

    The possibility of proton acceleration to very high energies in astrophysical sources may have unique observational consequences. In particular, the decay of secondary mesons created in the interaction of energetic protons with photons or nucleons gives rise to high-energy gamma rays and neutrinos with potentially observable fluxes. Recently, there has been considerable interest in the parameterization of the energy spectra of these secondaries. Less attention has been paid to the angular distributions, which may have an important effect on observational quantities and are required to address collisions between protons with different energies and an arbitrary scattering angle. In this work, we study the complete particle distributions of secondary mesons created in proton-proton collisions. We present parameterizations of the energy and rapidity distributions of secondary pions and kaons that reproduce results generated with the event generator PYTHIA to within ~10% in the bulk of the parameter space. The par...

  18. Effect of ion temperature on ion-acoustic solitary waves in a magnetized plasma in presence of superthermal electrons

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S. V.; Devanandhan, S.; Lakhina, G. S. [Indian Institute of Geomagnetism, Navi Mumbai (India); Bharuthram, R. [University of the Western Cape, Bellville (South Africa)

    2013-01-15

    Obliquely propagating ion-acoustic soliatry waves are examined in a magnetized plasma composed of kappa distributed electrons and fluid ions with finite temperature. The Sagdeev potential approach is used to study the properties of finite amplitude solitary waves. Using a quasi-neutrality condition, it is possible to reduce the set of equations to a single equation (energy integral equation), which describes the evolution of ion-acoustic solitary waves in magnetized plasmas. The temperature of warm ions affects the speed, amplitude, width, and pulse duration of solitons. Both the critical and the upper Mach numbers are increased by an increase in the ion temperature. The ion-acoustic soliton amplitude increases with the increase in superthermality of electrons. For auroral plasma parameters, the model predicts the soliton speed, amplitude, width, and pulse duration, respectively, to be in the range of (28.7-31.8) km/s, (0.18-20.1) mV/m; (590-167) m, and (20.5-5.25) ms, which are in good agreement with Viking observations.

  19. Energy loss in vehicle collisions from permanent deformation: an extension of the `Triangle Method'

    Science.gov (United States)

    Vangi, Dario; Begani, Filippo

    2013-06-01

    The paper presents an extension of the 'Triangle Method', to evaluate the energy loss in road accidents. The improvement of the method allows to evaluate the energy loss by both the colliding vehicles in car to car impacts, considering the main possible configurations of accident. The limits of applicability of the method are those of the Campbell's method [K.E. Campbell, Energy basis for collision severity, SAE paper 740565, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1974; A.G. Fonda, Principles of crush energy determination, SAE 1999-01-0106, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1999; N.S. Tumbas and R.A. Smith, Measurement protocol for quantifying vehicle damage from an energy basis point of view, SAE paper 880072, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1988; G.A. Nystrom, G. Kost, and S.M. Werner, Stiffness parameters for vehicle collision analysis, SAE paper 910119, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1991; J.A. Neptune, G.Y. Blair, and J.E. Flynn, A method for quantifying vehicle crush stiffness coefficients, SAE paper 920607, Society of Automotive Engineers, Inc., Warrendale, Pennsylvania, 1992]. The advantage over the usual methods are that the method does not require the knowledge of the stiffness of the vehicles and only two parameters are needed to define the damage geometry. The latter can be easily evaluated by visual inspection on a suitable photographical documentation of the damages, without the need to perform any direct measurement on the vehicles. Furthermore, the method can be used also in the very frequent cases in which some of the damage data about one of the vehicles are missing or in accidents involving lateral parts of the vehicle as zones near the wheels or the front, that have different behaviour from that tested in the classical crash tests. The error analysis developed shows that the errors due to the application of the extended

  20. Impact parameter and beam energy dependence for azimuthal asymmetry of direct photons and free protons in intermediate energy heavy-ion collisions

    Institute of Scientific and Technical Information of China (English)

    LIU Gui-Hua; MA Yu-Gang; CAI Xiang-Zhou; FANG De-Qing; SHEN Wen-Qing; TIAN Wen-Dong; WANG Kun

    2009-01-01

    Hard photon emitted from energetic heavy ion collisions is of very interesting since it does not experience the late-stage nuclear interaction, therefore it is useful to explore the early-stage information of matter phase. In this work, we have calculated the impact parameter and beam energy dependence for azimuthal asymmetry, characterized by directed transverse flow parameter F and elliptic asymmetry coefficient v2, of direct photons and the corresponding free protons in intermediate energy heavy-ion collisions. It is further shown the anti-correlated azimuthal asymmetry between direct photons and free protons.

  1. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC

    CERN Document Server

    Adamczyk, L; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, E C; Attri, A; Averichev, G S; Bai, X; Bairathi, V; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandenburg, J D; Brandin, A V; Bunzarov, I; Butterworth, J; Caines, H; Sánchez, M Calderón de la Barca; Campbell, J M; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chatterjee, A; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A I; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Hirsch, A; Hoffmann, G W; Horvat, S; Huang, T; Huang, X; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jentsch, A; Jia, J; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikoła, D P; Kisel, I; Kisiel, A; Kochenda, L; Koetke, D D; Kosarzewski, L K; Kraishan, A F; Kravtsov, P; Krueger, K; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, X; Li, C; Li, Y; Li, W; Lin, T; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, R; Ma, G L; Ma, Y G; Ma, L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Matis, H S; McDonald, D; McKinzie, S; Meehan, K; Mei, J C; Minaev, N G; Mioduszewski, S; Mishra, D; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Niida, T; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V A; Olvitt, D; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Pile, P; Pluta, J; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, A; Sharma, B; Sharma, M K; Shen, W Q; Shi, Z; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Singha, S; Skoby, M J; Smirnov, N; Smirnov, D; Solyst, W; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B; Sun, Z; Sun, X M; Sun, Y; Surrow, B; Svirida, D N; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A; Thäder, J; Thomas, J H; Timmins, A R; Tlusty, D; Todoroki, T; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbæk, F; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, G; Wang, J S; Wang, H; Wang, Y; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xiao, Z G; Xie, W; Xie, G; Xin, K; Xu, Y F; Xu, Q H; Xu, N; Xu, H; Xu, Z; Xu, J; Yang, S; Yang, Y; Yang, C; Yang, Q; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I -K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, Y; Zhang, J; Zhang, S; Zhang, Z; Zhang, J B; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2016-01-01

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from $\\sqrt{s_{NN}}=7.7$ GeV to 200 GeV. The third harmonic $v_3^2\\{2\\}=\\langle \\cos3(\\phi_1-\\phi_2)\\rangle$, where $\\phi_1-\\phi_2$ is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs $\\Delta\\eta = \\eta_1-\\eta_2$. Non-zero {\\vthree} is directly related to the previously observed large-$\\Delta\\eta$ narrow-$\\Delta\\phi$ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity Quark Gluon Plasma (QGP) phase. For sufficiently central collisions, $v_3^2\\{2\\}$ persist down to an energy of 7.7 GeV suggesting that QGP may be created even in these low energy collisions. In peripheral collisions at these low energies however, $v_3^2\\{2\\}$ is consistent with zero. When scaled by pseudorapidity density of charged particle multiplicity per participating nuc...

  2. Recent results on (anti)nucleus and (anti)hyperon production in nucleus-nucleus collisions at CERN SPS energies

    CERN Document Server

    Melkumov, G L; Anticic, T; Baatar, B; Barna, D; Bartke, J; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Botje, M; Bracinik, J; Bramm, R; Buncic, P; Cerny, V; Christakoglou, P; Chung, P; Chvala, O; Cramer, J G; Csató, P; Dinkelaker, P; Eckardt, V; Flierl, D; Fodor, Z; Foka, P; Friese, V; Gál, J; Gazdzicki, M; Genchev, V; Georgopoulos, G; Grebieszkow, K; Hegyi, S; Höhne, C; Kadija, K; Karev, A; Kikola, D; Gladysz-Dziadus, E; Kliemant, M; Kniege, S; Kolesnikov, V I; Kornas, E; Korus, R; Kowalski, M; Kraus, I; Kreps, M; Laszlo, A; Lacey, R; Van Leeuwen, M; Lvai, P; Litov, L; Lungwitz, B; Makariev, M; Malakhov, A I; Mateev, M; Melkumov, G L; Mischke, A; Mitrovski, M; Molnár, J; Mrówczynski, S; Nicolic, V; Pálla, G; Panagiotou, A D; Panayotov, D; Petridis, A; Peryt, W; Pikna, M; Pluta, J; Prindle, D; Pühlhofer, F; Renfordt, R; Roland, C; Roland5, G; Rybczynski, M; Rybicki, A; Sandoval, A; Schmitz, N; Schuster, T; Siklér, F; Sitár, B; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Seyboth, P; Strabel, C; Ströbele, H; Susa, T; Szentpetery, I; Sziklai, J; Szuba, M; Szymanski, P; Trubnikov, V; Varga, D; Vassiliou, M; Veres, G I; Vesztergombi, G; Vranic, D; Wlodarczyk, Z; Wojtaszek11, A; Yoo, I K; Zimnyi, J; Wetzler, A

    2007-01-01

    The NA49 experiment has collected comprehensive data on particle production in nucleus-nucleus collisions over the whole SPS beam energies range, the critical energy domain where the expected phase transition to a deconfined phase is expected to occur. The latest results from Pb+Pb collisions between 20$A$ GeV and 158$A$ GeV on baryon stopping and light nuclei production as well as those for strange hyperons are presented. The measured data on $p$, $\\bar{p}$, $\\Lambda$, $\\bar{\\Lambda}$, $\\Xi^-$ and $\\bar{\\Xi}^+$ production were used to evaluate the rapidity distributions of net-baryons at SPS energies and to compare with the results from the AGS and the RHIC for central Pb+Pb (Au+Au) collisions. The dependence of the yield ratios and the inverse slope parameter of the $m_t$ spectra on the collision energy and centrality, and the mass number of the produced nuclei $^3He$, $t$, $d$ and $\\bar{d}$ are discussed within coalescence and statistical approaches. Analysis of the total multiplicity exhibits remarkable a...

  3. Analysis of $\\pi^{0},\\eta$ and $\\omega$ mesons in pp collisions with a high energy photon trigger at ALICE

    CERN Document Server

    Yano, Satoshi

    High energy heavy ion collision is a powerful and unique tool to achieve the high density and temperature like the early universe. At normal temperature, partons are confined in nucleons and they can not move freely due to the asymp- totic freedom which is a property of the Quantum Chromo Dynamics (QCD). However, at high density and/or high temperature, they can be deconfined from nucleons. This phase is called the Quark Gluon Plasma (QGP). Hadron production measurements in proton-proton collisions at the Large Hadron Collider (LHC) energies can observe new phenomena which must be a frontier in the particle physics and allow validation of the predictive power of the QCD and can provide further constrains on pQCD theory for LHC energies. It is well known that the yield of high transvers momentum particles is suppressed in nucleus-nucleus collisions relative to that in proton-proton collisions. This effect is attributed to energy loss of parent partons or perhaps of hadrons after freeze-out. Since π 0 , η and...

  4. Centrality dependence of midrapidity density from GeV to TeV heavy-ion collisions in the effective-energy universality picture of hadroproduction

    CERN Document Server

    Sarkisyan, Edward K.G.; Sahoo, Raghunath; Sakharov, Alexander S.

    2016-01-01

    The dependence on centrality, or on the number of nucleon participants, of the midrapidity density of charged particles measured in heavy-ion collisions at the collision energy of about 20 GeV at RHIC to the highest LHC energy of 5 TeV is investigated within the recently proposed effective-energy approach. This approach relates multihadron production in different types of collisions by combining, under the proper scaling of the collision energy, the constituent quark picture with Landau relativistic hydrodynamics. The measurements are shown to be well described based on the similarity of multihadron production process in (anti)proton-proton interactions and heavy-ion collisions driven by the centrality-dependent effective energy of participants.

  5. Thermal Description of Particle Production in Au-Au Collisions at STAR Energies

    CERN Document Server

    Tawfik, A

    2013-01-01

    The hadron ratios measured in central Au-Au collisions are analysed by means of Hadron Resonance Gas (HRG) model over a wide range of nucleon-nucleon center-of-mass energies ranging from 7.7 to 200 GeV as offered by the STAR Beam Energy Scan I (BES-I). We restrict the discussion on STAR BES-I, because of large statistics and over all homogeneity of STAR measurements (one detector) against previous experiments. Over the last three decades, various heavy-ion experiments utilizing different detectors (different certainties) have been carried out. Regularities in produced particles at different energies haven been studied. The temperature and baryon chemical potential are deduced from fits of experimental ratios to thermal model calculations assuming chemical equilibrium. We find that the resulting freeze-out parameters using single hard-core value and point-like constituents of HRG are identical. This implies that the excluded-volume comes up with no effect on the extracted parameters. We compare the results wit...

  6. Probing the symmetry energy at high baryon density with heavy ion collisions

    CERN Document Server

    Greco, V; Di Toro, M; Wolter, H H

    2009-01-01

    The nuclear symmetry energy at densities above saturation density ($\\rho_0\\sim 0.16 fm^{-3}$) is poorly constrained theoretically and very few relevant experimental data exist. Its study is possible through Heavy Ion Collisions (HIC) at energies $E/A> 200$ MeV, particularly with beams of neutron-rich radioactive nuclei. The energy range implies that the momentum dependence of the isospin fields, i.e. the difference of the effective masses on protons and neutrons, also has to be investigated before a safe constraint on $\\esy(\\rho)$ is possible. We discuss the several observables which have been suggested, like $n/p$ emission and their collective flows and the ratio of meson yields with different isospin projection, $\\pi^-/\\pi^+$ and $K^0/K^+$. We point out several physical mechanisms that should be included in the theoretical models to allow a direct comparison to the more precise experiments which will be able to distinguish the isospin projection of the detected particles: CSR/Lanzhou, FAIR/GSI, RIBF/RIKEN, ...

  7. Isospin Effect on the Process of Multifragmentation and Dissipation at Intermediate Energy Heavy Ion Collisions

    CERN Document Server

    Liu Jian Ye; Zuo, W; Wang, S J; Zhao, Q; Guo, W J; Chen, B; Liu, Jian-Ye; Yang, Yan-Fang; Zuo, Wei; Wang, Shun-Jin; Zhao, Qiang; Guo, Wen-Jun; Chen, Bo

    2001-01-01

    In the simulation of intermediate energy heavy ion collisions by using the isospin dependent quantum molecular dynamics, the isospin effect on the process of multifragmentation and dissipation has been studied. It is found that the multiplicity of intermediate mass fragments $N_{imf}$ for the neutron-poor colliding system is always larger than that for the neutron-rich system, while the quadrupole of single particle momentum distribution $Q_{zz}$ for the neutron-poor colliding system is smaller than that of the neutron-rich system for all projectile-target combinations studied at the beam energies from about 50MeV/nucleon to 150MeV/nucleon. Since $Q_{zz}$ depends strongly on isospin dependence of in-medium nucleon-nucleon cross section and weakly on symmetry potential at the above beam energies, it may serve as a good probe to extract the information on the in-medium nucleon-nucleon cross section. The correlation between the multiplicity $N_{imf}$ of intermediate mass fragments and the total numer of charged ...

  8. Study of the energy dependence of the underlying event in proton-antiproton collisions

    Science.gov (United States)

    Aaltonen, T.; Albrow, M.; Amerio, S.; Amidei, D.; Anastassov, A.; Annovi, A.; Antos, J.; Apollinari, G.; Appel, J. A.; Arisawa, T.; Artikov, A.; Asaadi, J.; Ashmanskas, W.; Auerbach, B.; Aurisano, A.; Azfar, F.; Badgett, W.; Bae, T.; Barbaro-Galtieri, A.; Barnes, V. E.; Barnett, B. A.; Barria, P.; Bartos, P.; Bauce, M.; Bedeschi, F.; Behari, S.; Bellettini, G.; Bellinger, J.; Benjamin, D.; Beretvas, A.; Bhatti, A.; Bland, K. R.; Blumenfeld, B.; Bocci, A.; Bodek, A.; Bortoletto, D.; Boudreau, J.; Boveia, A.; Brigliadori, L.; Bromberg, C.; Brucken, E.; Budagov, J.; Budd, H. S.; Burkett, K.; Busetto, G.; Bussey, P.; Butti, P.; Buzatu, A.; Calamba, A.; Camarda, S.; Campanelli, M.; Canelli, F.; Carls, B.; Carlsmith, D.; Carosi, R.; Carrillo, S.; Casal, B.; Casarsa, M.; Castro, A.; Catastini, P.; Cauz, D.; Cavaliere, V.; Cerri, A.; Cerrito, L.; Chen, Y. C.; Chertok, M.; Chiarelli, G.; Chlachidze, G.; Cho, K.; Chokheli, D.; Clark, A.; Clarke, C.; Convery, M. E.; Conway, J.; Corbo, M.; Cordelli, M.; Cox, C. A.; Cox, D. J.; Cremonesi, M.; Cruz, D.; Cuevas, J.; Culbertson, R.; d'Ascenzo, N.; Datta, M.; de Barbaro, P.; Demortier, L.; Deninno, M.; D'Errico, M.; Devoto, F.; Di Canto, A.; Di Ruzza, B.; Dittmann, J. R.; Donati, S.; D'Onofrio, M.; Dorigo, M.; Driutti, A.; Ebina, K.; Edgar, R.; Elagin, A.; Erbacher, R.; Errede, S.; Esham, B.; Farrington, S.; Fernández Ramos, J. P.; Field, R.; Flanagan, G.; Forrest, R.; Franklin, M.; Freeman, J. C.; Frisch, H.; Funakoshi, Y.; Galloni, C.; Garfinkel, A. F.; Garosi, P.; Gerberich, H.; Gerchtein, E.; Giagu, S.; Giakoumopoulou, V.; Gibson, K.; Ginsburg, C. M.; Giokaris, N.; Giromini, P.; Glagolev, V.; Glenzinski, D.; Gold, M.; Goldin, D.; Golossanov, A.; Gomez, G.; Gomez-Ceballos, G.; Goncharov, M.; González López, O.; Gorelov, I.; Goshaw, A. T.; Goulianos, K.; Gramellini, E.; Grosso-Pilcher, C.; Group, R. C.; Guimaraes da Costa, J.; Hahn, S. R.; Han, J. Y.; Happacher, F.; Hara, K.; Hare, M.; Harr, R. F.; Harrington-Taber, T.; Hatakeyama, K.; Hays, C.; Heinrich, J.; Herndon, M.; Hocker, A.; Hong, Z.; Hopkins, W.; Hou, S.; Hughes, R. E.; Husemann, U.; Hussein, M.; Huston, J.; Introzzi, G.; Iori, M.; Ivanov, A.; James, E.; Jang, D.; Jayatilaka, B.; Jeon, E. J.; Jindariani, S.; Jones, M.; Joo, K. K.; Jun, S. Y.; Junk, T. R.; Kambeitz, M.; Kamon, T.; Karchin, P. E.; Kasmi, A.; Kato, Y.; Ketchum, W.; Keung, J.; Kilminster, B.; Kim, D. H.; Kim, H. S.; Kim, J. E.; Kim, M. J.; Kim, S. H.; Kim, S. B.; Kim, Y. J.; Kim, Y. K.; Kimura, N.; Kirby, M.; Knoepfel, K.; Kondo, K.; Kong, D. J.; Konigsberg, J.; Kotwal, A. V.; Kreps, M.; Kroll, J.; Kruse, M.; Kuhr, T.; Kurata, M.; Laasanen, A. T.; Lammel, S.; Lancaster, M.; Lannon, K.; Latino, G.; Lee, H. S.; Lee, J. S.; Leo, S.; Leone, S.; Lewis, J. D.; Limosani, A.; Lipeles, E.; Lister, A.; Liu, H.; Liu, Q.; Liu, T.; Lockwitz, S.; Loginov, A.; Lucchesi, D.; Lucá, A.; Lueck, J.; Lujan, P.; Lukens, P.; Lungu, G.; Lys, J.; Lysak, R.; Madrak, R.; Maestro, P.; Malik, S.; Manca, G.; Manousakis-Katsikakis, A.; Marchese, L.; Margaroli, F.; Marino, P.; Matera, K.; Mattson, M. E.; Mazzacane, A.; Mazzanti, P.; McNulty, R.; Mehta, A.; Mehtala, P.; Mesropian, C.; Miao, T.; Mietlicki, D.; Mitra, A.; Miyake, H.; Moed, S.; Moggi, N.; Moon, C. S.; Moore, R.; Morello, M. J.; Mukherjee, A.; Muller, Th.; Murat, P.; Mussini, M.; Nachtman, J.; Nagai, Y.; Naganoma, J.; Nakano, I.; Napier, A.; Nett, J.; Neu, C.; Nigmanov, T.; Nodulman, L.; Noh, S. Y.; Norniella, O.; Oakes, L.; Oh, S. H.; Oh, Y. D.; Oksuzian, I.; Okusawa, T.; Orava, R.; Ortolan, L.; Pagliarone, C.; Palencia, E.; Palni, P.; Papadimitriou, V.; Parker, W.; Pauletta, G.; Paulini, M.; Paus, C.; Phillips, T. J.; Piacentino, G.; Pianori, E.; Pilot, J.; Pitts, K.; Plager, C.; Pondrom, L.; Poprocki, S.; Potamianos, K.; Pranko, A.; Prokoshin, F.; Ptohos, F.; Punzi, G.; Redondo Fernández, I.; Renton, P.; Rescigno, M.; Rimondi, F.; Ristori, L.; Robson, A.; Rodriguez, T.; Rolli, S.; Ronzani, M.; Roser, R.; Rosner, J. L.; Ruffini, F.; Ruiz, A.; Russ, J.; Rusu, V.; Sakumoto, W. K.; Sakurai, Y.; Santi, L.; Sato, K.; Saveliev, V.; Savoy-Navarro, A.; Schlabach, P.; Schmidt, E. E.; Schwarz, T.; Scodellaro, L.; Scuri, F.; Seidel, S.; Seiya, Y.; Semenov, A.; Sforza, F.; Shalhout, S. Z.; Shears, T.; Shepard, P. F.; Shimojima, M.; Shochet, M.; Shreyber-Tecker, I.; Simonenko, A.; Sliwa, K.; Smith, J. R.; Snider, F. D.; Song, H.; Sorin, V.; St. Denis, R.; Stancari, M.; Stentz, D.; Strologas, J.; Sudo, Y.; Sukhanov, A.; Suslov, I.; Takemasa, K.; Takeuchi, Y.; Tang, J.; Tecchio, M.; Teng, P. K.; Thom, J.; Thomson, E.; Thukral, V.; Toback, D.; Tokar, S.; Tollefson, K.; Tomura, T.; Tonelli, D.; Torre, S.; Torretta, D.; Totaro, P.; Trovato, M.; Ukegawa, F.; Uozumi, S.; Vázquez, F.; Velev, G.; Vellidis, C.; Vernieri, C.; Vidal, M.; Vilar, R.; Vizán, J.; Vogel, M.; Volpi, G.; Wagner, P.; Wallny, R.; Wang, S. M.; Waters, D.; Wester, W. C.; Whiteson, D.; Wicklund, A. B.; Wilbur, S.; Williams, H. H.; Wilson, J. S.; Wilson, P.; Winer, B. L.; Wittich, P.; Wolbers, S.; Wolfe, H.; Wright, T.; Wu, X.; Wu, Z.; Yamamoto, K.; Yamato, D.; Yang, T.; Yang, U. K.; Yang, Y. C.; Yao, W.-M.; Yeh, G. P.; Yi, K.; Yoh, J.; Yorita, K.; Yoshida, T.; Yu, G. B.; Yu, I.; Zanetti, A. M.; Zeng, Y.; Zhou, C.; Zucchelli, S.; CDF Collaboration

    2015-11-01

    We study charged particle production (pT>0.5 GeV /c , |η |<0.8 ) in proton-antiproton collisions at total center-of-mass energies √{s }=300 GeV , 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of η -ϕ space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  9. 2006-2007 Academic training programme: QCD and high energy nuclear collision

    CERN Multimedia

    HR Department

    2007-01-01

    LECTURE SERIES 7, 8, 9 May QCD and high energy nuclear collisions D. Kharzeev, Brookhaven National Laboratory, USA 11:00 to 12:00 - Main Auditorium, Bldg. 500 on 7 and 8 May, Council Chamber on 9 May Six years ago, Relativistic Heavy Ion Collider at Brookhaven started colliding heavy nuclei at record center-of-mass energies of up to 200 GeV/nucleon. Very soon, the Large Hadron Collider at CERN will push the energy of the ions to an astounding 5 TeV/nucleon. What can be learnt from the experiments at these machines? What do we know about the physics of super--dense matter already? I will argue that heavy ion accelerators bring us to the new frontiers of physical knowledge by creating strong color fields and very high densities of partons, at which qualitatively new phenomena emerge. I will also discuss the cross-disciplinary implications for cosmology, astrophysics, and connections to condensed matter physics.

  10. 2006-2007 Academic training programme: QCD and high energy nuclear collisions

    CERN Multimedia

    HR Department

    2007-01-01

    LECTURE SERIES 7, 8, 9 May 2007 11:00 to 12:00 - Main Auditorium, Bldg. 500 on 7 and 8 May, Council Chamber on 9 May QCD and high energy nuclear collisions D. Kharzeev, Brookhaven National Laboratory, USA Six years ago, the Relativistic Heavy Ion Collider at Brookhaven started colliding heavy nuclei at record center-of-mass energies of up to 200 GeV/nucleon. Very soon, the Large Hadron Collider at CERN will push the energy of the ions to an astounding 5 TeV/nucleon. What can be learnt from the experiments at these machines? What do we know about the physics of super--dense matter already? I will argue that heavy ion accelerators bring us to the new frontiers of physical knowledge by creating strong color fields and very high densities of partons, at which qualitatively new phenomena emerge. I will also discuss the cross-disciplinary implications for cosmology, astrophysics, and connections to condensed matter physics.

  11. Energy dependence of multiplicity fluctuations in heavy ion collisions at the CERN SPS

    CERN Document Server

    Lungwitz, Benjamin

    2008-01-01

    In this work data of the NA49 experiment at CERN SPS on the energy dependence of multiplicity fluctuations in central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV, as well as the system size dependence at 158A GeV, is analysed for positively, negatively and all charged hadrons. Furthermore the rapidity and transverse momentum dependence of multiplicity fluctuations are studied. The experimental results are compared to predictions of statistical hadron-gas and string-hadronic models. It is expected that multiplicity fluctuations are sensitive to the phase transition to quark-gluon-plasma (QGP) and to the critical point of strongly interacting matter. It is predicted that both the onset of deconfinement, the lowest energy where QGP is created, and the critical point are located in the SPS energy range. Furthermore, the predictions for the multiplicity fluctuations of statistical and string-hadronic models are different, the experimental data might allow to distinguish between them. The used measure of mu...

  12. Study of the energy dependence of the underlying event in proton-antiproton collisions

    Energy Technology Data Exchange (ETDEWEB)

    Nodulman, L.; Aaltonen, T; Albrow, M; Amerio, S.; Amidei, D; Anastassov, A.; Annovi, A; Antos, J; Apollinari, G.; Appel, J A; Arisawa, T

    2015-11-23

    We study charged particle production (p(T) > 0.5 GeV/c, vertical bar eta vertical bar < 0.8) in proton-antiproton collisions at total center-of-mass energies root s = 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta - phi space: "toward", "away", and "transverse." The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the "underlying event." The transverse region is divided into a MAX and MIN transverse region, which helps separate the "hard component" (initial and final-state radiation) from the "beam-beam remnant" and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event is studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  13. Baseline measures for net-proton distributions in high energy heavy-ion collisions

    Science.gov (United States)

    Netrakanti, P. K.; Luo, X. F.; Mishra, D. K.; Mohanty, B.; Mohanty, A.; Xu, N.

    2016-03-01

    We report a systematic comparison of the recently measured cumulants of the net-proton distributions for 0-5% central Au + Au collisions in the first phase of the Beam Energy Scan (BES) Program at the Relativistic Heavy Collider facility to various kinds of possible baseline measures. These baseline measures correspond to an assumption that the proton and anti-proton distributions follow Poisson statistics, Binomial statistics, obtained from a transport model calculation and from a hadron resonance gas model. The higher order cumulant net-proton data for the center of mass energies (√{sNN}) of 19.6 and 27 GeV are observed to deviate from most of the baseline measures studied. The deviations are predominantly due to the difference in shape of the proton distributions between data and those obtained in the baseline measures. We also present a detailed study on the relevance of the independent production approach as a baseline for comparison with the measurements at various beam energies. Our studies point to the need of either more detailed baseline models for the experimental measurements or a description via QCD calculations in order to extract the exact physics process that leads to deviation of the data from the baselines presented.

  14. Charge Exchange in Low-Energy H, D + C4+ Collisions with Full Account of Electron Translation

    Directory of Open Access Journals (Sweden)

    A. Riera

    2002-03-01

    Full Text Available The effect of the anisotropy of the interaction potential on ion-diatom non-adiabatic collisions is analized by considering the influence of the anisotropy on orientation averaged total cross sections for charge transfer in H++H2(X1Σ+g collisions. We discuss the possibility of employing simpli ed methods such as an isotropic approximation, where only the electronic energies and interactions of a single orientation are necessary. The use of several isotropic calculations to evaluate the orientation averaged cross section is analized.

  15. Nuclear Stopping as A Probe to In-medium Nucleon-nucleon Cross Section in Intermediate Energy Heavy Ion Collisions

    CERN Document Server

    Liu Jian Ye; Wang, S J; Zuo, W; Zhao, Q; Yang Yong Feng; Liu, Jian-Ye; Guo, Wen-Jun; Wang, Shun-Jin; Zuo, Wei; Zhao, Qiang; Yang, Yan-Fang

    2001-01-01

    Using an isospin-dependent quantum molecular dynamics, nuclear stopping in intermediate heavy ion collisions has been studied. The calculation has been done for colliding systems with different neutron-proton ratios in beam energy ranging from 15MeV/u to 150MeV/u. It is found that, in the energy region from above Fermi energy to 150MeV/u, nuclear stopping is very sensitive to the isospin dependence of in-medium nucleon-nucleon cross section, but insensitive to symmetry potential. From this investigation, we propose that nuclear stopping can be used as a new probe to extract the information on the isospin dependence of in-medium nucleon-nucleon cross section in intermediate energy heavy ion collisions.

  16. Influence of collision energy and vibrational excitation on the dynamics for the H+HBr → H2 + Br reaction

    Indian Academy of Sciences (India)

    Yanhua Wang; Min Peng; Jianying Tong; Yuliang Wang

    2015-08-01

    Quasi-classical trajectory (QCT) calculations of H+HBr → H2 + Br reaction have been performed on a recently proposed ab initio potential energy surface. The reaction probability and integral cross section are found to be in fairly good agreement with the available quantum mechanical (QM) results on this surface. The behavior of reactivity is well consistent with properties of exothermic reaction. Once the energy of vibrational excited HBr is larger than the barrier height, the integral cross sections for the reaction diverge at very low collision energies close to the threshold, similarly to capture reaction. In addition, differential cross sections show that scattering of the product H2 shift from backward to forward directions as the collision energy and vibrational quantum number increase. All the theoretical findings are reasonably explained by the properties of the surface, as well as reactive mechanisms.

  17. Multiple collision effects on the antiproton production by high energy proton (100 GeV - 1000 GeV)

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Hiroshi; Powell, J.

    1987-01-01

    Antiproton production rates which take into account multiple collision are calculated using a simple model. Methods to reduce capture of the produced antiprotons by the target are discussed, including geometry of target and the use of a high intensity laser. Antiproton production increases substantially above 150 GeV proton incident energy. The yield increases almost linearly with incident energy, alleviating space charge problems in the high current accelerator that produces large amounts of antiprotons.

  18. What can we learn from the directed flow in heavy-ion collisions at BES RHIC energies?

    CERN Document Server

    Ivanov, Yu B

    2016-01-01

    Analysis of directed flow ($v_1$) of protons, antiprotons and pions in heavy-ion collisions is performed in the range of collision energies $\\sqrt{s_{NN}}$ = 2.7--39 GeV. Simulations have been done within a three-fluid model employing a purely hadronic equation of state (EoS) and two versions of the EoS with deconfinement transitions: a first-order phase transition and a smooth crossover transition. The crossover EoS is unambiguously preferable for the description of the most part of experimental data in this energy range. The directed flow indicates that the crossover deconfinement transition takes place in semicentral Au+Au collisions in a wide range of collision energies 4 \\lsim\\sqrt{s_{NN}}\\lsim$ 30 GeV. The obtained results suggest that the deconfinement EoS's in the quark-gluon sector should be stiffer at high baryon densities than those used in the calculation. The latter finding is in agreement with that discussed in astrophysics.

  19. Single Muon Production And Implications For Charm In Center Of Mass Energies = 20 Gev Gold+gold Collisions

    CERN Document Server

    Glenn, A M

    2004-01-01

    The PHENIX experiment, located at the Brookhaven National Laboratory's Relativistic Heavy Ion Collider, is designed to study high energy proton+proton and nucleus+nucleus collisions in order to characterize hot and dense nuclear matter. This dissertation presents the first analysis of single muon production in sNN = 200 GeV Au+Au reactions. Implications of the forward rapidity measurements for charm production are discussed. Motivation for charm production measurements and the role of open charm in characterizing the medium created in relativistic heavy ion collisions are presented, and the importance of measurements at forward rapidity is established. The results of this study are compared to relevant calculations and related measurements at RHIC. The number of muons produced from charm decays is found to scale with the number of binary collisions within large experimental errors over the studied kinematic region.

  20. Ultra-high energy collisions in static space-times: single versus multi-black hole cases

    CERN Document Server

    Zaslavskii, O B

    2014-01-01

    We consider collision of two particles near static electrically charged extremal black holes and elucidate the conditions under which the energy in the centre of mass frame E_{c.m.} grows unbounded. For a single black hole, we generalize the results obtained earlier for the Reissner-Nordstr\\"om metric, to distorted black holes. In the multi-black hole space-time, qualitatively new features appear. If the point of collision is close to at least two horizons simultaneously, unbounded E_{c.m.} are possible (i) without fine-tuning of particles' parameters, (ii) for an arbitrary mutual orientation of two velocities. Such a combination of properties (i) and (ii) has no analogues in the single black hole case and facilitates the condition of getting unbounded E_{c.m.}. Collisions in the electro-vacuum Majumdar-Papapetrou metric (several extremal black holes in equilibrium) is analyzed explicitly.

  1. Oscillations of moments in high-energy nucleus-nucleus collisions

    Institute of Scientific and Technical Information of China (English)

    YANG; Hongyan(

    2001-01-01

    [1]Bialas, A., Peschanski, R., Moments of rapidity distributions as a measure of short-range fluctuations in high-energy colli-sions, Nucl. Phys. B, 1986, 273: 703-718.[2]Wu Yuanfang, Liu Lianshou, Self-affinity of multiplicity fluctuation in the phase space of multiparticle production, Phys. Rev.Lett., 1993, 70: 3197-3200.[3]Zhang Yang, The study of intemittency and multifractal in high energy collisions, Doctor Thesis, Institute of Particle Physics,Hua-Zhong Normal University, 1995.[4]Dremin, I. M. , Quantum chromodynamics and multiplicity distributions, Physics-Uspekhi, 1994, 37(8): 715-736.[5]Dremin, I. M., Arena, V., Boca, G. et al., Cumulant to factorial moment ratio and multiplicity data, Phys. Len. B,1994, 336: 119-124.[6]Ugoccioni, R., Stuctures in multiplicity distributions and oscillations of moments, in Proceedings of the 26th International Symposium on Multiparticle Dynamics (eds. Dias de Deus, J. , Sa, P. , Pimenta, M. et al. ), Singapore: World Scientific,1997, 208-219.[7]Capella, A., Dremin, I. M., Nechitailo, V. A. et al., Moment analysis of multiplicity distributions, Z. Phys. C, 1997,75: 89-94.[8]Dremin, I. M. , Nechitailo, V. A., Biyajima, M. et al. , Comparative analysis of multiplicity distributions in inelastic pro-cesses for different colliding particles and nuclei, Phys. Lett. B, 1997, 403: 149-154.[9]Wang Shaoshun, Zhang Jie, Wang Zhaomin et al., Cumulant to factorial moment ratio of multiplicity distributions of pp inter-actions at 400GeV/c, Phys. Rev. D, 1997, 56: 1-5.[10]Kittel, W., Chekanov, S. V., Mangeol, D. J. et al., Multiplicities, fluctuations and QCD, interplay between soft and hard physics? Nucl. Phys. Proc. Suppl., 1999, 71: 90-99.[11]Adamovich, M. I., Aggarwal, M. M., Alexandrov, Y. A. et al., (EMU01 Collaboration) Rapidity density distribution in 16O, 28Si, 32S, 197Au, and 208Pb induced heavy-ion interactions at 4A-200A GeV, Phys. Rev. Lett., 1992, 69: 745-748.[12]Cai Xu, Huang

  2. The impact of energy conservation in transport models on the $\\pi^-/\\pi^+$ multiplicity ratio in heavy-ion collisions and the symmetry energy

    CERN Document Server

    Cozma, M D

    2014-01-01

    The charged pion multiplicity ratio in intermediate energy central heavy-ion collisions has been proposed as a suitable observable to constrain the high density dependence of the isovector part of the equation of state, with contradicting results. Using an upgraded version of the T\\"ubingen QMD transport model, which allows the conservation of energy at a local or global level by accounting for the potential energy of hadrons in two-body collisions and leading thus to particle production threshold shifts, we demonstrate that compatible constraints for the symmetry energy stiffness can be extracted from pion multiplicity and elliptic flow observables. Nevertheless, pion multiplicities are proven to be highly sensitive to the yet unknown isovector part of the in-medium $\\Delta$(1232) potential which hinders presently the extraction of meaningful information on the high density dependence of the symmetry energy. A solution to this problem together with the inclusion of contributions presently neglected, such as ...

  3. Stopping effects in U+U collisions with a beam energy of 520 MeV/nucleon

    CERN Document Server

    Luo, Xiao-Feng; Shao, Ming; Wu, Ke-Jun; Li, Cheng; Chen, Hong-Fang

    2007-01-01

    A Relativistic Transport Model (ART1.0) is applied to simulate the stopping effects in tip-tip and body-body U+U collisions, at a beam kinetic energy of 520 MeV/nucleon. Our simulation results have demonstrated that both central collisions of the two extreme orientations can achieve full stopping, and also form a bulk of hot, dense nuclear matter with a sufficiently large volume and long duration, due to the largely deformed uranium nuclei. The nucleon sideward flow in the tip-tip collisions is nearly 3 times larger than that in body-body ones at normalized impact parameter $b/b_{max}<0.5$, and that the body-body central collisions have a largest negative nucleon elliptic flow $v_{2}=-12%$ in contrast to zero in tip-tip ones. Thus the extreme circumstance and the novel experimental observables in tip-tip and body-body collisions can provide a good condition and sensitive probe to study the nuclear EoS, respectively. The Cooling Storage Ring (CSR) External Target Facility (ETF) to be built at Lanzhou, China...

  4. Quantum dynamics of vibrational excitations and vibrational charge transfer processes in H+ + O2 collisions at collision energy 23 eV

    Indian Academy of Sciences (India)

    Saieswari Amaran; Sanjay Kumar

    2009-09-01

    Quantum mechanical study of vibrational state-resolved differential cross sections and transition probabilities for both the elastic/inelastic and the charge transfer processes have been carried out in the H+ + O2 collisions at the experimental collision energy of 23 eV. The quantum dynamics has been performed within the vibrational close-coupling rotational infinite-order sudden approximation framework employing our newly obtained quasi-diabatic potential energy surfaces corresponding to the ground and the first excited electronic states which have been computed using ab initio procedures and Dunning’s correlation consistent-polarized valence triple zeta basis set at the multireference configuration interaction level of accuracy. The present theoretical results for elastic/inelastic processes provide an overall agreement with the available state-selected experimental data, whereas the results for the charge transfer channel show some variance in comparison with those of experiments and are similar to the earlier theoretical results obtained using model effective potential based on projected valence bond method and using semi-empirical diatomics-in-molecules potential. The possible reason for discrepancies and the likely ways to improve the results are discussed in terms of the inclusion of higher excited electronic states into the dynamics calculation.

  5. A top quark pair production event from proton-proton collisions recorded by ATLAS with LHC stable beams at a collision energy of 13 TeV

    CERN Multimedia

    ATLAS Collaboration

    2015-01-01

    Display of a candidate boosted top quark pair production event from proton-proton collisions recorded by ATLAS with LHC stable beams at a collision energy of 13 TeV. The red line shows the path of a muon with transverse momentum around 50 GeV through the detector. The dashed line shows the direction of the missing transverse momentum, which has a magnitude of about 470 GeV. The green and yellow bars indicate energy deposits in the liquid argon and scintillating-tile calorimeters, from these deposits 4 small-radius (R=0.4) jets are identified with transverse momenta between 70 and 300 GeV. Three of these small-radius jets are re-clustered into the leading large-radius (R=1.0) jet (not shown explicitly) with a transverse momentum of about 600 GeV and a jet mass of about 180 GeV, near the top quark mass. One of these three jets in addition to the fourth jet above 70 GeV are identified as having originated from b-quarks. Tracks reconstructed from hits in the inner tracking detector are shown as arcs curving in th...

  6. Nonplanar positron-acoustic Gardner solitary waves in electron-positron-ion plasmas with superthermal electrons and positrons

    Energy Technology Data Exchange (ETDEWEB)

    Uddin, M. J., E-mail: josim.phys2007@gmail.com; Alam, M. S.; Mamun, A. A. [Department of Physics, Jahangirnagar University, Savar, Dhaka-1342 (Bangladesh)

    2015-02-15

    Nonplanar (cylindrical and spherical) positron-acoustic (PA) Gardner solitary waves (SWs) in an unmagnetized plasma system consisting of immobile positive ions, mobile cold positrons, and superthermal (kappa distributed) hot positrons and electrons are investigated. The modified Gardner equation is derived by using the reductive perturbation technique. The effects of cylindrical and spherical geometries, superthermal parameter of hot positrons and electrons, relative temperature ratios, and relative number density ratios on the PA Gardner SWs are studied by using the numerical simulations. The implications of our results in various space and laboratory plasma environments are briefly discussed.

  7. Electroweak Measurements in Electron-Positron Collisions at W-Boson-Pair Energies at LEP

    CERN Document Server

    Schael, S.; Bruneliere, R.; Buskulic, D.; De Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Jezequel, S.; Lees, J.P.; Lucotte, A.; Martin, F.; Merle, E.; Minard, M.N.; Nief, J.Y.; Odier, P.; Pietrzyk, B.; Trocme, B.; Bravo, S.; Casado, M.P.; Chmeissani, M.; Comas, P.; Crespo, J.M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Grauges, E.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Orteu, S.; Pacheco, A.; Park, I.C.; Perlas, J.; Riu, I.; Ruiz, H.; Sanchez, F.; Colaleo, A.; Creanza, D.; De Filippis, N.; De Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Bazarko, A.; Becker, U.; Boix, G.; Bird, F.; Blucher, E.; Bonvicini, B.; Bright-Thomas, P.; Barklow, T.; Buchmuller, O.; Cattaneo, M.; Cerutti, F.; Ciulli, V.; Clerbaux, B.; Drevermann, H.; Forty, R.W.; Frank, M.; Greening, T.C.; Hagelberg, R.; Halley, A.W.; Gianotti, F.; Girone, M.; Hansen, J.B.; Harvey, J.; Jacobsen, R.; Hutchcroft, D.E.; Janot, P.; Jost, B.; Knobloch, J.; Kado, M.; Lehraus, I.; Lazeyras, P.; Maley, P.; Mato, P.; May, J.; Moutoussi, A.; Pepe-Altarelli, M.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schmitt, B.; Schneider, O.; Tejessy, W.; Teubert, F.; Tomalin, I.R.; Tournefier, E.; 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Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, An.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.; Abbiendi, G.; Ackerstaff, K.; Ainsley, C.; Akesson, P.F.; Alexander, G.; Allison, J.; Altekamp, N.; Ametewee, K.; Anagnostou, G.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Bailey, I.; Barberio, E.; Barillari, T.; Barlow, R.J.; Bartoldus, R.; Batley, R.J.; Baumann, S.; Bechtle, P.; Bechtluft, J.; Beeston, C.; Behnke, T.; Bell, K.W.; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bentvelsen, S.; Berlich, P.; Bethke, S.; Biebel, O.; Boeriu, O.; Blobel, V.; Bloodworth, I.J.; Bloomer, J.E.; Bobinski, M.; Bock, P.; Bonacorsi, D.; Bosch, H.M.; Boutemeur, M.; Bouwens, B.T.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, R.M.; Burckhart, H.J.; Burgard, C.; Burgin, R.; Cammin, J.; Campana, S.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, D.G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Csilling, A.; Cuffiani, M.; Dado, S.; Dallapiccola, C.; Dallavalle, M.; Dallison, S.; de Jong, S.; De Roeck, A.; Dervan, P.; De Wolf, E.A.; del Pozo, L.A.; Desch, K.; Dienes, B.; Dixit, M.S.; do Couto e Silva, E.; Donkers, M.; Doucet, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Edwards, J.E.G.; Estabrooks, P.G.; Etzion, E.; Evans, H.G.; Evans, M.; Fabbri, F.; Fanti, M.; Fath, P.; Feld, L.; Ferrari, P.; Fiedler, F.; Fierro, M.; Fischer, H.M.; Fleck, I.; Folman, R.; Fong, D.G.; Ford, M.; Foucher, M.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geddes, N.I.; Geich-Gimbel, C.; Geralis, T.; Giacomelli, G.; Giacomelli, P.; Giacomelli, R.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Giunta, M.; Glenzinski, D.; Goldberg, J.; Goodrick, M.J.; Gorn, W.; Graham, K.; Grandi, C.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hart, P.A.; Hartmann, C.; Hauke, A.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hillier, S.J.; Hilse, T.; Hobson, P.R.; Hocker, A.; Hoffman, K.; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Hughes-Jones, R.E.; Huntemeyer, P.; Hutchcroft, D.E.; Igo-Kemenes, P.; Imrie, D.C.; Ingram, M.R.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeffreys, P.W.; Jeremie, H.; Jimack, M.; Joly, A.; Jones, C.R.; Jones, G.; Jones, M.; Jones, R.W.L.; Jost, U.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; King, B.J.; Kirk, J.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Koetke, D.S.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, R.V.; Kramer, T.; Krasznahorkay, A., Jr.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Lahmann, R.; Lai, W.P.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lazic, D.; Lee, A.M.; Lefebvre, E.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lewis, C.; Liebisch, R.; Lillich, J.; List, B.; List, J.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, A.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Marchant, T.E.; Markus, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Matthews, W.; Mattig, P.; McDonald, W.J.; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McNab, A.I.; McPherson, R.A.; Mendez-Lorenzo, P.; Meijers, F.; Menges, W.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, N.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Morii, M.; Muller, U.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nellen, B.; Nijjhar, B.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oh, A.; Okpara, A.; Oldershaw, N.J.; Omori, T.; Oreglia, M.J.; Orito, S.; Pahl, C.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Pearce, M.J.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, D.E.; Poffenberger, P.; Polok, J.; Poli, B.; Pooth, O.; Posthaus, A.; Przybycien, M.; Przysiezniak, H.; Quadt, A.; Rabbertz, K.; Rees, D.L.; Rembser, C.; Renkel, P.; Rick, H.; Rigby, D.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rooke, A.; Ros, E.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rosvick, M.; Routenburg, P.; Rozen, Y.; Runge, K.; Runolfsson, O.; Ruppel, U.; Rust, D.R.; Rylko, R.; Sachs, K.; Saeki, T.; Sahr, O.; Sarkisyan, E.K.G.; Sasaki, M.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schenk, P.; Schieck, J.; Schmitt, S.; Schorner-Sadenius, T.; Schroder, M.; Schultz-Coulon, H.C.; Schulz, M.; Schumacher, M.; Schutz, P.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skillman, A.; Skuja, A.; Smith, A.M.; Smith, T.J.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Spano, F.; Springer, R.W.; Sproston, M.; Stahl, A.; Steiert, M.; Stephens, K.; Steuerer, J.; Stockhausen, B.; Stoll, K.; Strom, D.; Strohmer, R.; Strumia, F.; Stumpf, L.; Surrow, B.; Szymanski, P.; Tafirout, R.; Talbot, S.D.; Tanaka, S.; Taras, P.; Tarem, S.; Taylor, R.J.; Tasevsky, M.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; von Torne, E.; Torrence, E.; Towers, S.; Toya, D.; Trefzger, T.; Trigger, I.; Trocsanyi, Z.; Tsukamoto, T.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Utzat, P.; Vachon, B.; Van Kooten, R.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Vikas, P.; Vincter, M.; Vokurka, E.H.; Vollmer, C.F.; Voss, H.; Vossebeld, J.; Wackerle, F.; Wagner, A.; Waller, D.; Ward, C.P.; Ward, D.R.; Ward, J.J.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; White, J.S.; Wilkens, B.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wotton, S.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.; Zivkovic, L.

    2013-01-01

    Electroweak measurements performed with data taken at the electron-positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3~fb$^{-1}$ collected by the four LEP experiments ALEPH, DELPHI, L3 and OPAL, at centre-of-mass energies ranging from $130~GeV$ to $209~GeV$. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron-positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose-Einstein correlations between the two W decay systems arising ...

  8. Collisions between low-energy electrons and small polyatomic targets of biological relevance

    Science.gov (United States)

    Hargreaves, Leigh

    2016-05-01

    Over the last decade, cross section measurements and calculations for DNA prototype molecules have received significant attention from the collisions community, due to the potential applications of this data in modelling electron transport through biological matter with a view to improving radiation dosimetry. Such data are additionally interesting from a fundamental aspect, as small carbon-based molecules are ideal targets for considering effects including target conformation, long-range dynamical interactions and coupling effects between the various degrees of freedom on the scattering properties of the target. At the California State University Fullerton, we have made a series of measurements of the elastic, vibrationally inelastic and electronically inelastic cross sections for a variety of small polyatomic targets, including water and the basic alcohols, ethylene, toluene and several fluorinated alkanes. These processes are important in a range of applications, primarily for modelling electron transport and thermalization, and energy deposition to a biological media. The data were obtained using a high resolution electron energy-loss spectrometer, operating in a crossed beam configuration with a moveable aperture gas source. The gas source design facilitates both an expedient and highly accurate method of removing background signal, and removes uncertainties from the data due to uncertainties in the beam profile. We have also performed scattering calculations employing the Schwinger Multichannel method, in collaboration with the California institute of technology, to compare with our measurements. In this talk, I will present an overview of our recent data and future research plans.

  9. F IASCO: a multidetector optimized for semiperipheral heavy ion collisions at Fermi energies

    Science.gov (United States)

    Bini, M.; Casini, G.; Olmi, A.; Poggi, G.; Stefanini, A. A.; Bardelli, L.; Bartoli, A.; Bidini, L.; Coppi, C.; Del Carmine, P.; Mangiarotti, A.; Maurenzig, P. R.; Pasquali, G.; Piantelli, S.; Poggi, S.; Taccetti, N.; Vanzi, E.

    2003-12-01

    The F IASCO multidetector is a low-threshold apparatus, optimized for the investigation of peripheral to semi-central collisions in heavy ion reactions at Fermi energies. It consists of three types of detectors. The first detector layer is a shell of 24 position-sensitive Parallel Plate Avalanche Detectors (PPADs), covering about 70% of the forward hemisphere, which measure the velocity vectors of the heavy ( Z≳10) reaction products. Below and around the grazing angle, behind the most forward PPADs, there are 96 Δ E-E silicon telescopes (with thickness of 200 and 500 μm, respectively); they are mainly used to measure the energy of the projectile-like fragment and to identify its charge and, via the time-of-flight of the PPADs, also its mass. Finally, behind most of the PPADs there are 158 (or 182, depending on the configuration) scintillation detectors, mostly of the phoswich type, which cover 25-30% of the forward hemisphere; they identify both light charged particles ( Z=1,2) and intermediate mass fragments (3⩽ Z≲20), measuring also their time-of-flight.

  10. Energy loss, hadronization and hadronic interactions of heavy flavors in relativistic heavy-ion collisions

    CERN Document Server

    Cao, Shanshan; Bass, Steffen A

    2015-01-01

    We construct a theoretical framework to describe the evolution of heavy flavors produced in relativistic heavy-ion collisions. The in-medium energy loss of heavy quarks is described using our modified Langevin equation that incorporates both quasi-elastic scatterings and the medium-induced gluon radiation. The space-time profiles of the fireball is described by a (2+1)-dimensional hydrodynamics simulation. A hybrid model of fragmentation and coalescence is utilized for heavy quark hadronization, after which the produced heavy mesons together with the soft hadrons produced from the bulk QGP are fed into the hadron cascade UrQMD model to simulate the subsequent hadronic interactions. We find that the medium-induced gluon radiation contributes significantly to heavy quark energy loss at high $p_\\mathrm{T}$; heavy-light quark coalescence enhances heavy meson production at intermediate $p_\\mathrm{T}$; and scatterings inside the hadron gas further suppress the $D$ meson $R_\\mathrm{AA}$ at large $p_\\mathrm{T}$ and e...

  11. FIASCO: a multidetector optimized for semiperipheral heavy ion collisions at Fermi energies

    Energy Technology Data Exchange (ETDEWEB)

    Bini, M.; Casini, G.; Olmi, A. E-mail: olmi@fi.infn.it; Poggi, G. E-mail: poggi@fi.infn.it; Stefanini, A.A.; Bardelli, L.; Bartoli, A.; Bidini, L.; Coppi, C.; Del Carmine, P.; Mangiarotti, A.; Maurenzig, P.R.; Pasquali, G.; Piantelli, S.; Poggi, S.; Taccetti, N.; Vanzi, E

    2003-12-11

    The FIASCO multidetector is a low-threshold apparatus, optimized for the investigation of peripheral to semi-central collisions in heavy ion reactions at Fermi energies. It consists of three types of detectors. The first detector layer is a shell of 24 position-sensitive Parallel Plate Avalanche Detectors (PPADs), covering about 70% of the forward hemisphere, which measure the velocity vectors of the heavy (Z > or approx. 10) reaction products. Below and around the grazing angle, behind the most forward PPADs, there are 96 {delta}E-E silicon telescopes (with thickness of 200 and 500 {mu}m, respectively); they are mainly used to measure the energy of the projectile-like fragment and to identify its charge and, via the time-of-flight of the PPADs, also its mass. Finally, behind most of the PPADs there are 158 (or 182, depending on the configuration) scintillation detectors, mostly of the phoswich type, which cover 25-30% of the forward hemisphere; they identify both light charged particles (Z=1,2) and intermediate mass fragments (3{<=}Z < or approx. 20), measuring also their time-of-flight.

  12. A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions

    CERN Document Server

    Aaltonen, Timo Antero; Amerio, Silvia; Amidei, Dante E; Anastassov, Anton Iankov; Annovi, Alberto; Antos, Jaroslav; Apollinari, Giorgio; Appel, Jeffrey A; Arisawa, Tetsuo; Artikov, Akram Muzafarovich; Asaadi, Jonathan A; Ashmanskas, William Joseph; Auerbach, Benjamin; Aurisano, Adam J; Azfar, Farrukh A; Badgett, William Farris; Bae, Taegil; Barbaro-Galtieri, Angela; Barnes, Virgil E; Barnett, Bruce Arnold; Barria, Patrizia; Bartos, Pavol; Bauce, Matteo; Bedeschi, Franco; Behari, Satyajit; Bellettini, Giorgio; Bellinger, James Nugent; Benjamin, Douglas P; Beretvas, Andrew F; Bhatti, Anwar Ahmad; Bland, Karen Renee; Blumenfeld, Barry J; Bocci, Andrea; Bodek, Arie; Bortoletto, Daniela; Boudreau, Joseph Francis; Boveia, Antonio; Brigliadori, Luca; Bromberg, Carl Michael; Brucken, Erik; Budagov, Ioulian A; Budd, Howard Scott; Burkett, Kevin Alan; Busetto, Giovanni; Bussey, Peter John; Butti, Pierfrancesco; Buzatu, Adrian; Calamba, Aristotle; Camarda, Stefano; Campanelli, Mario; Canelli, Florencia; Carls, Benjamin; Carlsmith, Duncan L; Carosi, Roberto; Carrillo Moreno, Salvador; Casal Larana, Bruno; Casarsa, Massimo; Castro, Andrea; Catastini, Pierluigi; Cauz, Diego; Cavaliere, Viviana; Cerri, Alessandro; Cerrito, Lucio; Chen, Yen-Chu; Chertok, Maxwell Benjamin; Chiarelli, Giorgio; Chlachidze, Gouram; Cho, Kihyeon; Chokheli, Davit; Clark, Allan Geoffrey; Clarke, Christopher Joseph; Convery, Mary Elizabeth; Conway, John Stephen; Corbo, Matteo; Cordelli, Marco; Cox, Charles Alexander; Cox, David Jeremy; Cremonesi, Matteo; Cruz Alonso, Daniel; Cuevas Maestro, Javier; Culbertson, Raymond Lloyd; D'Ascenzo, Nicola; Datta, Mousumi; de Barbaro, Pawel; Demortier, Luc M; Marchese, Luigi Marchese; Deninno, Maria Maddalena; Devoto, Francesco; D'Errico, Maria; Di Canto, Angelo; Di Ruzza, Benedetto; Dittmann, Jay Richard; D'Onofrio, Monica; Donati, Simone; Dorigo, Mirco; Driutti, Anna; Ebina, Koji; Edgar, Ryan Christopher; Erbacher, Robin D; Errede, Steven Michael; Esham, Benjamin; Farrington, Sinead Marie; Fernández Ramos, Juan Pablo; Field, Richard D; Flanagan, Gene U; Forrest, Robert David; Franklin, Melissa EB; Freeman, John Christian; Frisch, Henry J; Funakoshi, Yujiro; Galloni, Camilla; Garfinkel, Arthur F; Garosi, Paola; Gerberich, Heather Kay; Gerchtein, Elena A; Giagu, Stefano; Giakoumopoulou, Viktoria Athina; Gibson, Karen Ruth; Ginsburg, Camille Marie; Giokaris, Nikos D; Giromini, Paolo; Glagolev, Vladimir; Glenzinski, Douglas Andrew; Gold, Michael S; Goldin, Daniel; Golossanov, Alexander; Gomez, Gervasio; Gomez-Ceballos, Guillelmo; Goncharov, Maxim T; González López, Oscar; Gorelov, Igor V; Goshaw, Alfred T; Goulianos, Konstantin A; Gramellini, Elena; Grosso-Pilcher, Carla; Guimaraes da Costa, Joao; Hahn, Stephen R; Han, Ji-Yeon; Happacher, Fabio; Hara, Kazuhiko; Hare, Matthew Frederick; Harr, Robert Francis; Harrington-Taber, Timothy; Hatakeyama, Kenichi; Hays, Christopher Paul; Heinrich, Joel G; Herndon, Matthew Fairbanks; Hocker, James Andrew; Hong, Ziqing; Hopkins, Walter Howard; Hou, Suen Ray; Hughes, Richard Edward; Husemann, Ulrich; Hussein, Mohammad; Huston, Joey Walter; Introzzi, Gianluca; Iori, Maurizio; Ivanov, Andrew Gennadievich; James, Eric B; Jang, Dongwook; Jayatilaka, Bodhitha Anjalike; Jeon, Eun-Ju; Jindariani, Sergo Robert; Jones, Matthew T; Joo, Kyung Kwang; Jun, Soon Yung; Junk, Thomas R; Kambeitz, Manuel; Kamon, Teruki; Karchin, Paul Edmund; Kasmi, Azeddine; Kato, Yukihiro; Ketchum, Wesley Robert; Keung, Justin Kien; Kilminster, Benjamin John; Kim, DongHee; Kim, Hyunsoo; Kim, Jieun; Kim, Min Jeong; Kim, Soo Bong; Kim, Shin-Hong; Kim, Young-Kee; Kim, Young-Jin; Kimura, Naoki; Kirby, Michael H; Knoepfel, Kyle James; Kondo, Kunitaka; Kong, Dae Jung; Konigsberg, Jacobo; Kotwal, Ashutosh Vijay; Kreps, Michal; Kroll, IJoseph; Kruse, Mark Charles; Kuhr, Thomas; Kurata, Masakazu; Laasanen, Alvin Toivo; Lammel, Stephan; Lancaster, Mark; Lannon, Kevin Patrick; Latino, Giuseppe; Lee, Hyun Su; Lee, Jaison; Leo, Sabato; Leone, Sandra; Lewis, Jonathan D; Limosani, Antonio; Lipeles, Elliot David; Lister, Alison; Liu, Qiuguang; Liu, Tiehui Ted; Lockwitz, Sarah E; Loginov, Andrey Borisovich; Lucà, Alessandra; Lucchesi, Donatella; Lueck, Jan; Lujan, Paul Joseph; Lukens, Patrick Thomas; Lungu, Gheorghe; Lys, Jeremy E; Lysak, Roman; Madrak, Robyn Leigh; Maestro, Paolo; Malik, Sarah Alam; Manca, Giulia; Manousakis-Katsikakis, Arkadios; Margaroli, Fabrizio; Marino, Christopher Phillip; Matera, Keith; Mattson, Mark Edward; Mazzacane, Anna; Mazzanti, Paolo; McNulty, Ronan; Mehta, Andrew; Mehtala, Petteri; Mesropian, Christina; Miao, Ting; Mietlicki, David John; Mitra, Ankush; Miyake, Hideki; Moed, Shulamit; Moggi, Niccolo; Moon, Chang-Seong; Moore, Ronald Scott; Morello, Michael Joseph; Mukherjee, Aseet; Muller, Thomas; Murat, Pavel A; Mussini, Manuel; Nachtman, Jane Marie; Nagai, Yoshikazu; Naganoma, Junji; Nakano, Itsuo; Napier, Austin; Nett, Jason Michael; Nigmanov, Turgun S; Nodulman, Lawrence J; Noh, Seoyoung; Norniella Francisco, Olga; Oakes, Louise Beth; Oh, Seog Hwan; Oh, Young-do; Okusawa, Toru; Orava, Risto Olavi; Ortolan, Lorenzo; Pagliarone, Carmine Elvezio; Palencia, Jose Enrique; Palni, Prabhakar; Papadimitriou, Vaia; Parker, William Chesluk; Pauletta, Giovanni; Paulini, Manfred; Paus, Christoph Maria Ernst; Phillips, Thomas J; Piacentino, Giovanni M; Pianori, Elisabetta; Pilot, Justin Robert; Pitts, Kevin T; Plager, Charles; Pondrom, Lee G; Poprocki, Stephen; Potamianos, Karolos Jozef; Prokoshin, Fedor; Pranko, Aliaksandr Pavlovich; Ptohos, Fotios K; Punzi, Giovanni; Redondo Fernández, Ignacio; Renton, Peter B; Rescigno, Marco; Rimondi, Franco; Ristori, Luciano; Robson, Aidan; Rodriguez, Tatiana Isabel; Rolli, Simona; Ronzani, Manfredi; Roser, Robert Martin; Rosner, Jonathan L; Ruffini, Fabrizio; Ruiz Jimeno, Alberto; Russ, James S; Rusu, Vadim Liviu; Sakumoto, Willis Kazuo; Sakurai, Yuki; Santi, Lorenzo; Sato, Koji; Saveliev, Valeri; Savoy-Navarro, Aurore; Schlabach, Philip; Schmidt, Eugene E; Schwarz, Thomas A; Scodellaro, Luca; Scuri, Fabrizio; Seidel, Sally C; Seiya, Yoshihiro; Semenov, Alexei; Sforza, Federico; Shalhout, Shalhout Zaki; Shears, Tara G; Shepard, Paul F; Shimojima, Makoto; Shochet, Melvyn J; Shreyber-Tecker, Irina; Simonenko, Alexander V; Sliwa, Krzysztof Jan; Smith, John Rodgers; Snider, Frederick Douglas; Sorin, Maria Veronica; Song, Hao; Stancari, Michelle Dawn; St Denis, Richard Dante; Stentz, Dale James; Strologas, John; Sudo, Yuji; Sukhanov, Alexander I; Suslov, Igor M; Takemasa, Ken-ichi; Takeuchi, Yuji; Tang, Jian; Tecchio, Monica; Teng, Ping-Kun; Thom, Julia; Thomson, Evelyn Jean; Thukral, Vaikunth; Toback, David A; Tokar, Stanislav; Tollefson, Kirsten Anne; Tomura, Tomonobu; Tonelli, Diego; Torre, Stefano; Torretta, Donatella; Totaro, Pierluigi; Trovato, Marco; Ukegawa, Fumihiko; Uozumi, Satoru; Vázquez-Valencia, Elsa Fabiola; Velev, Gueorgui; Vellidis, Konstantinos; Vernieri, Caterina; Vidal Marono, Miguel; Vilar Cortabitarte, Rocio; Vizán Garcia, Jesus Manuel; Vogel, Marcelo; Volpi, Guido; Wagner, Peter; Wallny, Rainer S; Wang, Song-Ming; Waters, David S; Wester, William Carl; Whiteson, Daniel O; Wicklund, Arthur Barry; Wilbur, Scott; Williams, Hugh H; Wilson, Jonathan Samuel; Wilson, Peter James; Winer, Brian L; Wittich, Peter; Wolbers, Stephen A; Wolfe, Homer; Wright, Thomas Roland; Wu, Xin; Wu, Zhenbin; Yamamoto, Kazuhiro; Yamato, Daisuke; Yang, Tingjun; Yang, Un-Ki; Yang, Yu Chul; Yao, Wei-Ming; Yeh, Gong Ping; Yi, Kai; Yoh, John; Yorita, Kohei; Yoshida, Takuo; Yu, Geum Bong; Yu, Intae; Zanetti, Anna Maria; Zeng, Yu; Zhou, Chen; Zucchelli, Stefano

    2015-01-01

    We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  13. Vortical fluid and $\\Lambda$ spin correlations in high-energy heavy-ion collisions

    CERN Document Server

    Pang, Long-Gang; Wang, Qun; Wang, Xin-Nian

    2016-01-01

    Fermions become polarized in a vortical fluid due to spin-vorticity coupling. The spin polarization density is proportional to the local fluid vorticity at the next-to-leading order of a gradient expansion in a quantum kinetic theory. Spin correlations of two $\\Lambda$-hyperons can therefore reveal the vortical structure of the dense matter in high-energy heavy-ion collisions. We employ a (3+1)D viscous hydrodynamic model with event-by-event fluctuating initial conditions from A MultiPhase Transport (AMPT) model to calculate the vorticity distributions and $\\Lambda$ spin correlations. The azimuthal correlation of the transverse spin is shown to have a cosine form plus an offset due to a circular structure of the transverse vorticity around the beam direction and global spin polarization. The longitudinal spin correlation shows a structure of vortex-pairing in the transverse plane due to the convective flow of hot spots in the radial direction. The dependence on colliding energy, rapidity, centrality and sensi...

  14. A Study of the Energy Dependence of the Underlying Event in Proton-Antiproton Collisions

    CERN Document Server

    Aaltonen, Timo Antero; Amidei, Dante E; Anastassov, Anton Iankov; Annovi, Alberto; Antos, Jaroslav; Apollinari, Giorgio; Appel, Jeffrey A; Arisawa, Tetsuo; Artikov, Akram Muzafarovich; Asaadi, Jonathan A; Ashmanskas, William Joseph; Auerbach, Benjamin; Aurisano, Adam J; Azfar, Farrukh A; Badgett, William Farris; Bae, Taegil; Barbaro-Galtieri, Angela; Barnes, Virgil E; Barnett, Bruce Arnold; Barria, Patrizia; Bartos, Pavol; Bauce, Matteo; Bedeschi, Franco; Behari, Satyajit; Bellettini, Giorgio; Bellinger, James Nugent; Benjamin, Douglas P; Beretvas, Andrew F; Bhatti, Anwar Ahmad; Bland, Karen Renee; Blumenfeld, Barry J; Bocci, Andrea; Bodek, Arie; Bortoletto, Daniela; Boudreau, Joseph Francis; Boveia, Antonio; Brigliadori, Luca; Bromberg, Carl Michael; Brucken, Erik; Budagov, Ioulian A; Budd, Howard Scott; Burkett, Kevin Alan; Busetto, Giovanni; Bussey, Peter John; Butti, Pierfrancesco; Buzatu, Adrian; Calamba, Aristotle; Camarda, Stefano; Campanelli, Mario; Canelli, Florencia; Carls, Benjamin; Carlsmith, Duncan L; Carosi, Roberto; Carrillo Moreno, Salvador; Casal Larana, Bruno; Casarsa, Massimo; Castro, Andrea; Catastini, Pierluigi; Cauz, Diego; Cavaliere, Viviana; Cerri, Alessandro; Cerrito, Lucio; Chen, Yen-Chu; Chertok, Maxwell Benjamin; Chiarelli, Giorgio; Chlachidze, Gouram; Cho, Kihyeon; Chokheli, Davit; Clark, Allan Geoffrey; Clarke, Christopher Joseph; Convery, Mary Elizabeth; Conway, John Stephen; Corbo, Matteo; Cordelli, Marco; Cox, Charles Alexander; Cox, David Jeremy; Cremonesi, Matteo; Cruz Alonso, Daniel; Cuevas Maestro, Javier; Culbertson, Raymond Lloyd; D'Ascenzo, Nicola; Datta, Mousumi; de Barbaro, Pawel; Demortier, Luc M; Marchese, Luigi; Deninno, Maria Maddalena; Devoto, Francesco; D'Errico, Maria; Di Canto, Angelo; Di Ruzza, Benedetto; Dittmann, Jay Richard; D'Onofrio, Monica; Donati, Simone; Dorigo, Mirco; Driutti, Anna; Ebina, Koji; Edgar, Ryan Christopher; Erbacher, Robin D; Errede, Steven Michael; Esham, Benjamin; Farrington, Sinead Marie; Fernández Ramos, Juan Pablo; Field, Richard D; Flanagan, Gene U; Forrest, Robert David; Franklin, Melissa EB; Freeman, John Christian; Frisch, Henry J; Funakoshi, Yujiro; Galloni, Camilla; Garfinkel, Arthur F; Garosi, Paola; Gerberich, Heather Kay; Gerchtein, Elena A; Giagu, Stefano; Giakoumopoulou, Viktoria Athina; Gibson, Karen Ruth; Ginsburg, Camille Marie; Giokaris, Nikos D; Giromini, Paolo; Glagolev, Vladimir; Glenzinski, Douglas Andrew; Gold, Michael S; Goldin, Daniel; Golossanov, Alexander; Gomez, Gervasio; Gomez-Ceballos, Guillelmo; Goncharov, Maxim T; González López, Oscar; Gorelov, Igor V; Goshaw, Alfred T; Goulianos, Konstantin A; Gramellini, Elena; Grosso-Pilcher, Carla; Guimaraes da Costa, Joao; Hahn, Stephen R; Han, Ji-Yeon; Happacher, Fabio; Hara, Kazuhiko; Hare, Matthew Frederick; Harr, Robert Francis; Harrington-Taber, Timothy; Hatakeyama, Kenichi; Hays, Christopher Paul; Heinrich, Joel G; Herndon, Matthew Fairbanks; Hocker, James Andrew; Hong, Ziqing; Hopkins, Walter Howard; Hou, Suen Ray; Hughes, Richard Edward; Husemann, Ulrich; Hussein, Mohammad; Huston, Joey Walter; Introzzi, Gianluca; Iori, Maurizio; Ivanov, Andrew Gennadievich; James, Eric B; Jang, Dongwook; Jayatilaka, Bodhitha Anjalike; Jeon, Eun-Ju; Jindariani, Sergo Robert; Jones, Matthew T; Joo, Kyung Kwang; Jun, Soon Yung; Junk, Thomas R; Kambeitz, Manuel; Kamon, Teruki; Karchin, Paul Edmund; Kasmi, Azeddine; Kato, Yukihiro; Ketchum, Wesley Robert; Keung, Justin Kien; Kilminster, Benjamin John; Kim, DongHee; Kim, Hyunsoo; Kim, Jieun; Kim, Min Jeong; Kim, Soo Bong; Kim, Shin-Hong; Kim, Young-Kee; Kim, Young-Jin; Kimura, Naoki; Kirby, Michael H; Knoepfel, Kyle James; Kondo, Kunitaka; Kong, Dae Jung; Konigsberg, Jacobo; Kotwal, Ashutosh Vijay; Kreps, Michal; Kroll, IJoseph; Kruse, Mark Charles; Kuhr, Thomas; Kurata, Masakazu; Laasanen, Alvin Toivo; Lammel, Stephan; Lancaster, Mark; Lannon, Kevin Patrick; Latino, Giuseppe; Lee, Hyun Su; Lee, Jaison; Leo, Sabato; Leone, Sandra; Lewis, Jonathan D; Limosani, Antonio; Lipeles, Elliot David; Lister, Alison; Liu, Qiuguang; Liu, Tiehui Ted; Lockwitz, Sarah E; Loginov, Andrey Borisovich; Lucà, Alessandra; Lucchesi, Donatella; Lueck, Jan; Lujan, Paul Joseph; Lukens, Patrick Thomas; Lungu, Gheorghe; Lys, Jeremy E; Lysak, Roman; Madrak, Robyn Leigh; Maestro, Paolo; Malik, Sarah Alam; Manca, Giulia; Manousakis-Katsikakis, Arkadios; Margaroli, Fabrizio; Marino, Christopher Phillip; Matera, Keith; Mattson, Mark Edward; Mazzacane, Anna; Mazzanti, Paolo; McNulty, Ronan; Mehta, Andrew; Mehtala, Petteri; Mesropian, Christina; Miao, Ting; Mietlicki, David John; Mitra, Ankush; Miyake, Hideki; Moed, Shulamit; Moggi, Niccolo; Moon, Chang-Seong; Moore, Ronald Scott; Morello, Michael Joseph; Mukherjee, Aseet; Muller, Thomas; Murat, Pavel A; Mussini, Manuel; Nachtman, Jane Marie; Nagai, Yoshikazu; Naganoma, Junji; Nakano, Itsuo; Napier, Austin; Nett, Jason Michael; Nigmanov, Turgun S; Nodulman, Lawrence J; Noh, Seoyoung; Norniella Francisco, Olga; Oakes, Louise Beth; Oh, Seog Hwan; Oh, Young-do; Okusawa, Toru; Orava, Risto Olavi; Ortolan, Lorenzo; Pagliarone, Carmine Elvezio; Palencia, Jose Enrique; Palni, Prabhakar; Papadimitriou, Vaia; Parker, William Chesluk; Pauletta, Giovanni; Paulini, Manfred; Paus, Christoph Maria Ernst; Phillips, Thomas J; Piacentino, Giovanni M; Pianori, Elisabetta; Pilot, Justin Robert; Pitts, Kevin T; Plager, Charles; Pondrom, Lee G; Poprocki, Stephen; Potamianos, Karolos Jozef; Prokoshin, Fedor; Pranko, Aliaksandr Pavlovich; Ptohos, Fotios K; Punzi, Giovanni; Redondo Fernández, Ignacio; Renton, Peter B; Rescigno, Marco; Rimondi, Franco; Ristori, Luciano; Robson, Aidan; Rodriguez, Tatiana Isabel; Rolli, Simona; Ronzani, Manfredi; Roser, Robert Martin; Rosner, Jonathan L; Ruffini, Fabrizio; Ruiz Jimeno, Alberto; Russ, James S; Rusu, Vadim Liviu; Sakumoto, Willis Kazuo; Sakurai, Yuki; Santi, Lorenzo; Sato, Koji; Saveliev, Valeri; Savoy-Navarro, Aurore; Schlabach, Philip; Schmidt, Eugene E; Schwarz, Thomas A; Scodellaro, Luca; Scuri, Fabrizio; Seidel, Sally C; Seiya, Yoshihiro; Semenov, Alexei; Sforza, Federico; Shalhout, Shalhout Zaki; Shears, Tara G; Shepard, Paul F; Shimojima, Makoto; Shochet, Melvyn J; Shreyber-Tecker, Irina; Simonenko, Alexander V; Sliwa, Krzysztof Jan; Smith, John Rodgers; Snider, Frederick Douglas; Sorin, Maria Veronica; Song, Hao; Stancari, Michelle Dawn; St Denis, Richard Dante; Stentz, Dale James; Strologas, John; Sudo, Yuji; Sukhanov, Alexander I; Suslov, Igor M; Takemasa, Ken-ichi; Takeuchi, Yuji; Tang, Jian; Tecchio, Monica; Teng, Ping-Kun; Thom, Julia; Thomson, Evelyn Jean; Thukral, Vaikunth; Toback, David A; Tokar, Stanislav; Tollefson, Kirsten Anne; Tomura, Tomonobu; Tonelli, Diego; Torre, Stefano; Torretta, Donatella; Totaro, Pierluigi; Trovato, Marco; Ukegawa, Fumihiko; Uozumi, Satoru; Vázquez-Valencia, Elsa Fabiola; Velev, Gueorgui; Vellidis, Konstantinos; Vernieri, Caterina; Vidal Marono, Miguel; Vilar Cortabitarte, Rocio; Vizán Garcia, Jesus Manuel; Vogel, Marcelo; Volpi, Guido; Wagner, Peter; Wallny, Rainer S; Wang, Song-Ming; Waters, David S; Wester, William Carl; Whiteson, Daniel O; Wicklund, Arthur Barry; Wilbur, Scott; Williams, Hugh H; Wilson, Jonathan Samuel; Wilson, Peter James; Winer, Brian L; Wittich, Peter; Wolbers, Stephen A; Wolfe, Homer; Wright, Thomas Roland; Wu, Xin; Wu, Zhenbin; Yamamoto, Kazuhiro; Yamato, Daisuke; Yang, Tingjun; Yang, Un-Ki; Yang, Yu Chul; Yao, Wei-Ming; Yeh, Gong Ping; Yi, Kai; Yoh, John; Yorita, Kohei; Yoshida, Takuo; Yu, Geum Bong; Yu, Intae; Zanetti, Anna Maria; Zeng, Yu; Zhou, Chen; Zucchelli, Stefano

    2015-11-23

    We study charged particle production in proton-antiproton collisions at 300 GeV, 900 GeV, and 1.96 TeV. We use the direction of the charged particle with the largest transverse momentum in each event to define three regions of eta-phi space; toward, away, and transverse. The average number and the average scalar pT sum of charged particles in the transverse region are sensitive to the modeling of the underlying event. The transverse region is divided into a MAX and MIN transverse region, which helps separate the hard component (initial and final-state radiation) from the beam-beam remnant and multiple parton interaction components of the scattering. The center-of-mass energy dependence of the various components of the event are studied in detail. The data presented here can be used to constrain and improve QCD Monte Carlo models, resulting in more precise predictions at the LHC energies of 13 and 14 TeV.

  15. Multiplicity distribution of final-state particles and different contributions of related Sources in nucleus-nucleus collisions at high energies

    Institute of Scientific and Technical Information of China (English)

    SUN Zhu; LIU Pu-Hu

    2008-01-01

    The final state particle multiplicity distributions in high-energy nucleus-nucleus collisions are described by two different sub-distributious contributed by a single nucleon.The Monte Carlo calculated results from the two sub-distributions and the participant-spectator model are compared and found to be in agreement with the experimental data of Au-Au collisions ats=130 AGeV and Pb-Pb collisions at 158 AGeV.

  16. Energy dependence of collective flow of neutrons and protons in [sup 197]Au + [sup 197]Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    Lambrecht, D.; Blaich, T.; Elze, T.W.; Emling, H.; Freiesleben, H.; Grimni, K.; Henning, W.; Holzmann, R.; Keller, J.G.; Klingler, H.; Kratz, J.V.; Kulessa, R.; Lange, S.; Leifels, Y.; Lubkiewicz, E.; Moore, E.F.; Prokopowicz, W.; Schmidt, R.; Schuetter, C.; Spies, H.; Stelzer, K.; Stroth, J.; Wajda, E.; Walus, W.; Zinser, M.; Zude, E.; Alard, J.P.; Basrak, Z.; Bastid, N.; Belayev, I.M.; Bini, M.; Bock, R.; Buta, A.; Caplar, R.; Cerruti, C.; Cindro, N.; Coffin, J.P.; Crouau, M.; Dupieux, P.; Eroe, J.; Fan, Z.G.; Fintz, P.; Fodor, Z.; Freifelder, R.; Fraysse, L.; Frolov, S.; Gobbi, A.; Grigorian, Y.; Guillaume, G.; Herrmann, N.; Hildenbrand, K.D.; Hoelbling, S.; Houari, O.; Jeong, S.C.; Jorio, M.; Jundt, F.; Kecskemeti, J.; Koncz, P.; Korchagin, Y.; Kotte, R.; Kraemer, M.; Kuhn, C.; Legrand, I.; Lebedev, A.; Maguire, C.; Manko, V.; Matulewicz, T.; Mgebrishvili, G.; Moesner, J.; Moisa, D.; Montarou, G.; Morel, P.; Neubert, W.; Olmi, A.; Pasquali, G.; Pelte, D.; Petrovici, M.; Poggi, G.; FOPI-collaboration

    1994-11-01

    We investigate the beam energy dependence of neutron and proton squeeze-out in collisions of [sup 197]Au + [sup 197]Au at E/A=400-800 MeV. The azimuthal anisotropy that describes the enhanced emission of mid-rapidity neutrons perpendicular to the reaction plane rises strongly with the transverse momentum of the neutrons. This dependence of the azimuthal anisotropy follows a universal curve - independent of beam energy - if the neutron momenta are measured in fractions of the projectile momentum per mass unit. Analogously, the kinetic energy spectra of mid-rapidity neutrons exhibit a universal behaviour as a function of the kinetic energy of the projectile. (orig.)

  17. Thermalization of dense hadronic matter in Au + Au collisions at energies available at the Facility for Antiproton and Ion Research

    Science.gov (United States)

    De, Somnath; De, Sudipan; Chattopadhyay, Subhasis

    2016-11-01

    The conditions of local thermodynamic equilibrium of baryons (nonstrange, strange) and mesons (strange) are presented for central Au + Au collisions at Facility for Antiproton and Ion Research (FAIR) energies using the microscopic transport model UrQMD. The net particle density, longitudinal-to-transverse pressure anisotropy, and inverse slope parameters of the energy spectra of nonstrange and strange hadrons are calculated inside a cell in the central region within rapidity window |y |evolution of the entropy densities at FAIR energies are found to be very similar to the ideal hydrodynamic behavior at top Relativistic Heavy Ion Collider (RHIC) energy.

  18. Implications of energy and momentum conservation for particle emission in A +A collisions at energies available at the CERN Super Proton Synchrotron

    Science.gov (United States)

    Szczurek, Antoni; Kiełbowicz, Mirosław; Rybicki, Andrzej

    2017-02-01

    We construct a simple model of heavy-ion collisions, local in the impact parameter plane, and appropriate for energies available at the CERN Super Proton Synchrotron (SPS). This model can be regarded as a new realization of the "fire-streak" approach, originally applied to studies of lower-energy nucleus-nucleus reactions. Starting from local energy and momentum conservation, we nicely describe the broadening of the pion rapidity distribution when going from central to peripheral Pb +Pb collisions at √{sN N}=17.3 GeV. The results of our calculations are compared with SPS experimental data. We discuss the resulting implications on the role of energy and momentum conservation for the dynamics of particle production in heavy-ion collisions. A specific space-time picture emerges, where the longitudinal evolution of the system strongly depends on the position in the impact parameter (bx,by ) plane. This picture is consistent with our earlier findings on the longitudinal evolution of the system as deduced from electromagnetic effects on charged-pion directed flow and can provide an explanation for specific low-pT phenomena seen in the fragmentation region of Pb +Pb collisions.

  19. Effect of superthermal electrons on dust-acoustic Gardner solitons in nonplanar geometry

    Indian Academy of Sciences (India)

    Deb Kumar Ghosh; Yday Narayan Ghosh; Prasanta Chatterjee; C S Wong

    2013-04-01

    The properties of nonplanar (cylindrical and spherical) dust-acoustic solitary waves (DASWs) in an unmagnetized, collisionless three-component dusty plasma, whose constituents are negatively charged cold dust fluid, superthermal/non-Maxwellian electrons (represented by kappa distribution) and Boltzmann distributed ions, are investigated by deriving the modified Gardner (MG) equation. The well-known reductive perturbation method is employed to derive the MG equation. The basic features of nonplanar DA Gardner solitons (GSs) are discussed. It is seen that the properties of nonplanar DAGSs (positive and negative) significantly differ as the value of spectral index changes.

  20. Ab Initio Potential Energy Surfaces and Quantum Dynamics of Rotational Inelastic Processes in the H+ Collision with CS

    CERN Document Server

    Kaur, Rajwant

    2016-01-01

    Rate coefficient for state-to-state rotational transitions in H+ collision with CS has been obtained using accurate quantum dynamical close-coupling calculations to interpret microwave astronomical observations. Accurate three dimensional ab initio potential energy surfaces have been computed for the ground state and low-lying excited states of H+ - CS system using internally contracted MRCI method and aug-cc-pVQZ basis sets. Rotational excitation and deexcitation integral cross sections are computed at low and ultra low collision energies, respectively. Resonances have been observed at very low energies typically below 50 cm-1. Among all the transitions, Deltaj=+1 and Deltaj=-1 are found to be predominant for excitation and deexcitation, respectively. Deexcitation cross section in the ultracold region is found to obey Wigner's threshold law. The magnitude of state-to-state excitation rate obtained is maximum for j'=1 in the temperature range 2-240 K while minimum for deexcitation in ultracold region. The rot...

  1. Dynamics of Energy Transfer and Soft-Landing in Collisions of Protonated Dialanine with Perfluorinated Self-Assembled Monolayer Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pratihar, Subha; Kohale, Swapnil C.; Bhakta, Dhruv G.; Laskin, Julia; Hase, William L.

    2014-11-21

    Chemical dynamics simulations are reported which provide atomistic details of collisions of protonated dialanine, ala2-H+, with a perfluorinateted octanethiolate self-assembled monolayer (F-SAM ) surface. The simulations are performed at collisions energy Ei of 5.0, 13.5, 22.5, 30.00, and 70 eV, and incident angles 0o 0 (normal) and grazing 45o. Excellent agreement with experiment (J. Am. Chem. Soc. 2000, 122, 9703-9714) is found for both the average fraction and distribution of the collision energy transferred to the ala2-H+ internal degrees of freedom. The dominant pathway for this energy transfer is to ala2-H+ vibration, but for Ei = 5.0 eV ~20% of the energy transfer is to ala2-H+ rotation. Energy transfer to ala2-H+ rotation decreases with increase in Ei and becomes negligible at high Ei. Three types of collisions are observed in the simulations: i.e. those for which ala2-H+ (1) directly scatters off the F-SAM surface; (2) sticks/physisorbs on//in the surface, but desorbs within the 10 ps numerical integration of the simulations; and (3) remains trapped (i.e. soft-landed) on/in the surface when the simulations are terminated. Penetration of the F-SAM by ala2-H+ is important for the latter two types of events. The trapped trajectories are expected to have relatively long residence times on the surface, since a previous molecular dynamics simulation (J. Phys. Chem. B 2014, 118, 5577-5588) shows that thermally accommodated ala2-H+ ions have an binding energy with the F-SAM surface of at least ~15 kcal/mol.

  2. The Spectator-Induced Electromagnetic Effect on Meson Production in Nucleus-Nucleus Collisions at SPS Energies

    Directory of Open Access Journals (Sweden)

    Rybicki Andrzej

    2012-12-01

    Full Text Available The electromagnetic interaction between the spectator system and the charged mesons produced in the course of the high energy heavy ion collision was studied experimentally and theoretically in earlier works [1,2]. This effect was found to result in very large distortions of the final state spectra of the produced mesons [3] and to bring new information on the space-time evolution of the non-perturbative meson production process [4]. In this paper a more extended analysis of this effect will be presented, including a comparative study between charged meson spectra produced in Pb+Pb collisions as well as collisions of Pb ions with smaller nuclei. The experimental results will be compared with Monte Carlo simulations, giving a fair overall understanding of the interplay between the strong and the electromagnetic interaction in the heavy ion collision. A universal behaviour of charged meson spectra emerges from the above comparative study. This gives a unique chance of using the spectator charge as a tool to study the space-time evolution of the high energy nucleus-nucleus reaction.

  3. Cold collisions of SH- with He: Potential energy surface and rate coefficients

    Science.gov (United States)

    Bop, C. T.; Trabelsi, T.; Hammami, K.; Mogren Al Mogren, M.; Lique, F.; Hochlaf, M.

    2017-09-01

    Collisional energy transfer under cold conditions is of great importance from the fundamental and applicative point of view. Here, we investigate low temperature collisions of the SH- anion with He. We have generated a three-dimensional potential energy surface (PES) for the SH-(X1Σ+)-He(1S) van der Waals complex. The ab initio multi-dimensional interaction PES was computed using the explicitly correlated coupled cluster approach with simple, double, and perturbative triple excitation in conjunction with the augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. The PES presents two minima located at linear geometries. Then, the PES was averaged over the ground vibrational wave function of the SH- molecule and the resulting two-dimensional PES was incorporated into exact quantum mechanical close coupling calculations to study the collisional excitation of SH- by He. We have computed inelastic cross sections among the 11 first rotational levels of SH- for energies up to 2500 cm-1. (De-)excitation rate coefficients were deduced for temperatures ranging from 1 to 300 K by thermally averaging the cross sections. We also performed calculations using the new PES for a fixed internuclear SH- distance. Both sets of results were found to be in reasonable agreement despite differences existing at low temperatures confirming that accurate predictions require the consideration of all internal degrees of freedom in the case of molecular hydrides. The rate coefficients presented here may be useful in interpreting future experimental work on the SH- negative ion colliding with He as those recently done for the OH--He collisional system as well as for possible astrophysical applications in case SH- would be detected in the interstellar medium.

  4. High resolution IR diode laser study of collisional energy transfer between highly vibrationally excited monofluorobenzene and CO2: the effect of donor fluorination on strong collision energy transfer.

    Science.gov (United States)

    Kim, Kilyoung; Johnson, Alan M; Powell, Amber L; Mitchell, Deborah G; Sevy, Eric T

    2014-12-21

    Collisional energy transfer between vibrational ground state CO2 and highly vibrationally excited monofluorobenzene (MFB) was studied using narrow bandwidth (0.0003 cm(-1)) IR diode laser absorption spectroscopy. Highly vibrationally excited MFB with E' = ∼41,000 cm(-1) was prepared by 248 nm UV excitation followed by rapid radiationless internal conversion to the electronic ground state (S1→S0*). The amount of vibrational energy transferred from hot MFB into rotations and translations of CO2 via collisions was measured by probing the scattered CO2 using the IR diode laser. The absolute state specific energy transfer rate constants and scattering probabilities for single collisions between hot MFB and CO2 were measured and used to determine the energy transfer probability distribution function, P(E,E'), in the large ΔE region. P(E,E') was then fit to a bi-exponential function and extrapolated to the low ΔE region. P(E,E') and the biexponential fit data were used to determine the partitioning between weak and strong collisions as well as investigate molecular properties responsible for large collisional energy transfer events. Fermi's Golden rule was used to model the shape of P(E,E') and identify which donor vibrational motions are primarily responsible for energy transfer. In general, the results suggest that low-frequency MFB vibrational modes are primarily responsible for strong collisions, and govern the shape and magnitude of P(E,E'). Where deviations from this general trend occur, vibrational modes with large negative anharmonicity constants are more efficient energy gateways than modes with similar frequency, while vibrational modes with large positive anharmonicity constants are less efficient at energy transfer than modes of similar frequency.

  5. Influence of collision energy on cross section and stereodynamical properties for the reaction H + OCl → OH + Cl

    Science.gov (United States)

    Zhou, Sheng-Wen; Wang, Yun-Hui; Lu, Rui-Feng

    2012-06-01

    The quasi-classical trajectory calculations are carried out for the reaction H + OCl → OH + Cl on the singlet ground state potential energy surface. The reaction probability for total angular momentum J = 0 and the integral cross section as a function of collision energy are presented. Furthermore, the product rotational alignment has been obtained, and the value tends to decrease with the increasing of collision energy with fluctuations. To investigate the collision-energy-dependent effects on chemical stereodynamics, the four generalized polarization-dependent differential cross sections (2π/σ)(dσ00/dωt), (2π/σ)(dσ20/dωt), (2π/σ)(dσ22+/dωt) and (2π/σ)(dσ21-/dωt), the distribution P(θr) of the angle between j'-k and the angle distribution P(ϕr) in terms of k-k'-j' correlation have also been calculated.

  6. Relics of Minijets amid Anisotropic Flows in High-energy Heavy-ion Collisions

    CERN Document Server

    Pang, Longgang; Wang, Xin-Nian

    2013-01-01

    Two dimensional low-$p_T$ dihadron correlations in azimuthal angle $\\phi$ and pseudo-rapidity $\\eta$ in high-energy heavy-ion collisions are investigated within both the HIJING Monte Carlo model and an event-by-event (3+1)D ideal hydrodynamic model. Without final-state interaction and collective expansion, dihadron correlations from HIJING simulations have a typical structure from minijets that contains a near-side two-dimensional peak and an away-side ridge along the $\\eta$-direction. In contrast, event-by-event (3+1)D ideal hydrodynamic simulations with fluctuating initial conditions from the HIJING+AMPT model produce a strong dihadron correlation that has an away-side as well as a near-side ridge. Relics of intrinsic dihadron correlation from minijets in the initial conditions still remain as superimposed on the two ridges. By varying initial conditions from HIJING+AMPT, we study effects of minijets, non-vanishing initial flow and longitudinal fluctuation on the final state dihadron correlations. With a la...

  7. Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy

    CERN Document Server

    Nosochkov, Y; Wang, MH; Fartoukh, S; Giovannozzi, M; de Maria, R; McIntosh, E

    2013-01-01

    Beta functions at two interaction points (IP) in the high luminosity LHC upgrade lattice (HL-LHC) at collision energy will be significantly reduced compared to the nominal LHC lattice. This will result in much higher beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme [1]. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The stronger effects of the IT field errors can be remedied by optimizing the IT field error specifications. The latter must satisfy two conditions: provide an acceptable DA and be compatible with realistically achievable field quality. Optimization of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gra...

  8. LHC Report: squeezing, low-energy collisions and an unidentified object

    CERN Multimedia

    Mike Lamont for the LHC team

    2015-01-01

    Commissioning of the nominal cycle – beam injection, ramp, squeezing – with low-intensity (probe) beams is progressing well. In parallel, the operators have started commissioning the machine with higher-intensity beams: a nominal bunch in each beam was taken to 6.5 TeV on Saturday, 2 May and, four days later, collisions were delivered to the experiments at the injection energy (450 GeV).   The other main commissioning thread involves preparations for higher beam intensities. To safely handle the higher number of protons per bunch and the higher number of bunches, a number of key systems have to be fully operational and set up with beam. These include the beam dump system, the beam interlock system and the collimation system. The latter involves around 100 individual pairs of jaws, each of which has to be positioned with respect to the beam during all phases of the machine cycle. Confirmation that everything is as it should be is made by deliberately provoking beam losses and c...

  9. Energy loss of ions in a magnetized plasma: conformity between linear response and binary collision treatments.

    Science.gov (United States)

    Nersisyan, H B; Zwicknagel, G; Toepffer, C

    2003-02-01

    The energy loss of a heavy ion moving in a magnetized electron plasma is considered within the linear response (LR) and binary collision (BC) treatments with the purpose to look for a connection between these two models. These two complementary approaches yield close results if no magnetic field is present, but there develop discrepancies with growing magnetic field at ion velocities that are lower than, or comparable with, the thermal velocity of the electrons. We show that this is a peculiarity of the Coulomb interaction which requires cutoff procedures to account for its singularity at the origin and its infinite range. The cutoff procedures in the LR and BC treatments are different as the order of integrations in velocity and in ordinary (Fourier) spaces is reversed in both treatments. While BC involves a velocity average of Coulomb logarithms, there appear in LR Coulomb logarithms of velocity averaged cutoffs. The discrepancies between LR and BC vanish, except for small contributions of collective modes, for smoothened potentials that require no cutoffs. This is shown explicitly with the help of an improved BC in which the velocity transfer is treated up to second order in the interaction in Fourier space.

  10. Electron-Transfer/Higher-Energy Collision Dissociation (EThcD)-Enabled Intact Glycopeptide/Glycoproteome Characterization

    Science.gov (United States)

    Yu, Qing; Wang, Bowen; Chen, Zhengwei; Urabe, Go; Glover, Matthew S.; Shi, Xudong; Guo, Lian-Wang; Kent, K. Craig; Li, Lingjun

    2017-09-01

    Protein glycosylation, one of the most heterogeneous post-translational modifications, can play a major role in cellular signal transduction and disease progression. Traditional mass spectrometry (MS)-based large-scale glycoprotein sequencing studies heavily rely on identifying enzymatically released glycans and their original peptide backbone separately, as there is no efficient fragmentation method to produce unbiased glycan and peptide product ions simultaneously in a single spectrum, and that can be conveniently applied to high throughput glycoproteome characterization, especially for N-glycopeptides, which can have much more branched glycan side chains than relatively less complex O-linked glycans. In this study, a redefined electron-transfer/higher-energy collision dissociation (EThcD) fragmentation scheme is applied to incorporate both glycan and peptide fragments in one single spectrum, enabling complete information to be gathered and great microheterogeneity details to be revealed. Fetuin was first utilized to prove the applicability with 19 glycopeptides and corresponding five glycosylation sites identified. Subsequent experiments tested its utility for human plasma N-glycoproteins. Large-scale studies explored N-glycoproteomics in rat carotid arteries over the course of restenosis progression to investigate the potential role of glycosylation. The integrated fragmentation scheme provides a powerful tool for the analysis of intact N-glycopeptides and N-glycoproteomics. We also anticipate this approach can be readily applied to large-scale O-glycoproteome characterization. [Figure not available: see fulltext.

  11. Constraint on Nuclear Symmetry Energy through Heavy RI Collision Experiment by Using SπRIT Device at RIBF-SAMURAI

    Science.gov (United States)

    Isobe, Tadaaki

    The symmetry energy of the nuclear Equation of State (EoS) is essential in many aspects of the astrophysics. However it has large ambiguity mainly for the dense region of ρ > ρ0. In order to give a constraint on the dencity dependent nuclear symmetry energy, an international experimental project at RIKEN-RIBF: SπRIT was launched. By using newly developed Time Projection Chamber (TPC) as a main device of SπRIT experiment, first heavy RI collision experiment was performed in the spring of 2016. In this experiment, charged π meson was measured as main observable as it is expected to be most sensitive to the symmetry energy.

  12. A new semiclassical decoupling scheme for electronic transitions in molecular collisions - Application to vibrational-to-electronic energy transfer

    Science.gov (United States)

    Lee, H.-W.; Lam, K. S.; Devries, P. L.; George, T. F.

    1980-01-01

    A new semiclassical decoupling scheme (the trajectory-based decoupling scheme) is introduced in a computational study of vibrational-to-electronic energy transfer for a simple model system that simulates collinear atom-diatom collisions. The probability of energy transfer (P) is calculated quasiclassically using the new scheme as well as quantum mechanically as a function of the atomic electronic-energy separation (lambda), with overall good agreement between the two sets of results. Classical mechanics with the new decoupling scheme is found to be capable of predicting resonance behavior whereas an earlier decoupling scheme (the coordinate-based decoupling scheme) failed. Interference effects are not exhibited in P vs lambda results.

  13. Small amplitude electron acoustic solitary waves in a magnetized superthermal plasma

    Science.gov (United States)

    Devanandhan, S.; Singh, S. V.; Lakhina, G. S.; Bharuthram, R.

    2015-05-01

    The propagation of electron acoustic solitary waves in a magnetized plasma consisting of fluid cold electrons, electron beam and superthermal hot electrons (obeying kappa velocity distribution function) and ion is investigated in a small amplitude limit using reductive perturbation theory. The Korteweg-de-Vries-Zakharov-Kuznetsov (KdV-ZK) equation governing the dynamics of electron acoustic solitary waves is derived. The solution of the KdV-ZK equation predicts the existence of negative potential solitary structures. The new results are: (1) increase of either the beam speed or temperature of beam electrons tends to reduce both the amplitude and width of the electron acoustic solitons, (2) the inclusion of beam speed and temperature pushes the allowed Mach number regime upwards and (3) the soliton width maximizes at certain angle of propagation (αm) and then decreases for α >αm . In addition, increasing the superthermality of the hot electrons also results in reduction of soliton amplitude and width. For auroral plasma parameters observed by Viking, the obliquely propagating electron-acoustic solitary waves have electric field amplitudes in the range (7.8-45) mV/m and pulse widths (0.29-0.44) ms. The Fourier transform of these electron acoustic solitons would result in a broadband frequency spectra with peaks near 2.3-3.5 kHz, thus providing a possible explanation of the broadband electrostatic noise observed during the Burst a.

  14. Pseudorapidity distributions of charged particles in Pb–Pb collisions at super proton synchrotron energies from the NA50 experiment

    Indian Academy of Sciences (India)

    Marek Idzik; M C Abreu; B Alessandro; C Alexa; R Arnaldi; M Atayan; C Baglin; A Baldit; M Bedjidian; S Beolè; V Boldea; P Bordalo; G Borges; A Bussière; L Capelli; C Castanier; J Castor; B Chaurand; I Chevrot; B Cheynis; E Chiavassa; C Cicalò; T Claudino; M P Comets; N Constans; S Constantinescu; P Cortese; A De Falco; N De Marco; G Dellacasa; A Devaux; S Dita; O Drapier; L Ducroux; B Espagnon; J Fargeix; P Force; M Gallio; Y K Gavrilov; C Gerschel; P Giubellino; M B Golubeva; M Gonin; A A Grigorian; S Grigorian; J Y Grossiord; F F Guber; A Guichard; H Gulkanyan; R Hakobyan; R Haroutunian; M Idzik; D Jouan; T L Karavitcheva; L Kluberg; A B Kurepin; Y Le Bornee; C Lourenço; P Macciotta; M Mac Cormick; A Marzari-Chiesa; M Masera; A Masoni; M Monteno; A Musso; P Petiau; A Piccotti; J R Pizzi; W L Prado da Silva; F Prino; G Puddu; C Quintans; L Ramello; S Ramos; P Rato Mendes; L Riccati; A Romana; H Santos; P Saturnini; E Scalas; E Scomparin; S Serci; R Shahoyan; F Sigaudo; S Silva; M Sitta; P Sonderegger; X Tarrago; N S Topilskaya; G L Usai; E Vercellin; L Villatte; N Willis; NA50 Collaboration

    2003-05-01

    We present the measurements of charged particle pseudorapidity distributions dch/d performed by the NA50 experiment in Pb–Pb collisions at the CERN SPS. Measurements were done at incident energies of 40 GeV ($\\sqrt{s}=8.77$ GeV) and 158 GeV ($\\sqrt{s}=17.3$ GeV) per nucleon over a broad impact parameter range. The multiplicity distributions are studied as a function of centrality using the number of participating nucleons (part), or the number of binary nucleon–nucleon collisions (coll). Their values at midrapidity exhibit a linear scaling with part at both energies. Particle yield increases approximately by a factor of 2 between $\\sqrt{s}=8.77$ GeV and $\\sqrt{s}=17.3$ GeV.

  15. Pseudorapidity distributions of charged particles in Pb-Pb collisions at super proton synchrotron energies from the NA50 experiment

    CERN Document Server

    Idzik, M; Alessandro, B; Alexa, C; Arnaldi, R; Atayan, M; Baglin, C; Baldit, A; Bedjidian, Marc; Beolè, S; Boldea, V; Bordalo, P; Borges, G; Bussière, A; Capelli, L; Castanier, C; Castor, J I; Chaurand, B; Chevrot, I; Cheynis, B; Chiavassa, E; Cicalò, C; Claudino, T; Comets, M P; Constans, N; Constantinescu, S; Cortese, P; De Falco, A; De Marco, N; Dellacasa, G; Devaux, A; Dita, S; Drapier, O; Ducroux, L; Espagnon, B; Fargeix, J; Force, P; Gallio, M; Gavrilov, Yu K; Gerschel, C; Giubellino, P; Golubeva, M B; Gonin, M; Grigorian, A A; Grigorian, S; Grossiord, J Y; Guber, F F; Guichard, A; Gulkanian, H R; Hakobyan, R S; Haroutunian, R; Jouan, D; Karavitcheva, T L; Kluberg, L; Kurepin, A B; Le Bornec, Y; Lourenço, C; MacCormick, M; Macciotta, P; Marzari-Chiesa, A; Masera, M; Masoni, A; Monteno, M; Musso, A; Petiau, P; Piccotti, A; Pizzi, J R; Prado da Silva, W L; Prino, F; Puddu, G; Quintans, C; Ramello, L; Ramos, S; Rato-Mendes, P; Riccati, L; Romana, A; Santos, H; Saturnini, P; Scalas, E; Scomparin, E; Serci, S; Shahoyan, R; Sigaudo, F; Silva, S; Sitta, M; Sonderegger, P; Tarrago, X; Topilskaya, N S; Usai, G L; Vercellin, Ermanno; Villatte, L; Willis, N

    2003-01-01

    We present the measurements of charged particle pseudorapidity distributions dN/sub ch//d eta performed by the NA50 experiment in Pb-Pb collisions at the CERN SPS. Measurements were done at incident energies of 40 GeV ( square root s = 8.77 GeV) and 158 GeV ( square root s = 17.3 GeV) per nucleon over a broad impact parameter range. The multiplicity distributions are studied as a function of centrality using the number of participating nucleons (N/sub part/), or the number of binary nucleon-nucleon collisions (N/sub coll/). Their values at midrapidity exhibit a linear scaling with N/sub part/ at both energies. Particle yield increases approximately by a factor of 2 between square root s = 8.77 GeV and square root s = 17.3 GeV. (5 refs).

  16. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    CERN Document Server

    Ray, R L

    2016-01-01

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid-Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid-Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  17. Energy dependence of fluctuations in p+p and Be+Be collisions from NA61/SHINE

    CERN Document Server

    Andronov, Evgeny

    2016-01-01

    The main aims of the NA61/SHINE experiment are to discover the critical point of strongly interacting matter and to study properties of the onset of deconfinement. For this goal a two dimensional scan of the phase diagram (T-$\\mu_{B}$) is being performed at the SPS with measurements of hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. It is expected that fluctuations of various dynamical quantities will increase close to the critical point. In this contribution recent results of measurements of fluctuations in p+p and Be+Be collisions at SPS energies are presented as well as comparisons with model predictions and corresponding data of other experiments are discussed.

  18. Statistical-noise reduction in correlation analysis of high-energy nuclear collisions with event-mixing

    Energy Technology Data Exchange (ETDEWEB)

    Ray, R.L., E-mail: ray@physics.utexas.edu; Bhattarai, P.

    2016-06-11

    The error propagation and statistical-noise reduction method of Reid and Trainor for two-point correlation applications in high-energy collisions is extended to include particle-pair references constructed by mixing two particles from all event-pair combinations within event subsets of arbitrary size. The Reid–Trainor method is also applied to other particle-pair mixing algorithms commonly used in correlation analysis of particle production from high-energy nuclear collisions. The statistical-noise reduction, inherent in the Reid–Trainor event-mixing procedure, is shown to occur for these other event-mixing algorithms as well. Monte Carlo simulation results are presented which verify the predicted degree of noise reduction. In each case the final errors are determined by the bin-wise particle-pair number, rather than by the bin-wise single-particle count.

  19. Experimental testing of ab initio potential energy surfaces: Stereodynamics of NO(A2Σ+) + Ne inelastic scattering at multiple collision energies

    Science.gov (United States)

    Luxford, Thomas F. M.; Sharples, Thomas R.; McKendrick, Kenneth G.; Costen, Matthew L.

    2016-11-01

    We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A2Σ+, v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm-1, and N' = 3 and 5-14 for collisions at an average energy of 1309 cm-1, respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A2Σ+)-Ne interaction at the collision energies used here. Sharp, forward scattered (<10°), peaks are observed in the experimental differential cross sections for a wide range of N' at both collision energies, which are not reproduced by theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A2Σ+)-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A2Σ+)-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment moments as a

  20. A simple nonbinary scattering model applicable to atomic collisions is crystals at 1ow energies

    DEFF Research Database (Denmark)

    Andersen, Hans Henrik; Sigmund, Peter

    1966-01-01

    the elliptic to the spherical potential are investigated. Special attention is paid to proper definitions of collision time and collision length which are important in collisions in crystals. Limitations to classical scattering arising from the uncertainty principle prove to be more serious than assumed......Presents the solution of a special scattering problem which may be important in the theory of slowing-down of atomic particles in crystals. A projectile moves along the centre axis of a regular ring of n equal atoms which are free and do not interact with each other. The interaction between...

  1. Measurement of the forward energy flow in $pp$ collisions at $\\sqrt{s}$= 7 TeV

    CERN Document Server

    Aaij, R; Adametz, A; Adeva, B; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves Jr, A A; Amato, S; Amhis, Y; Anderlini, L; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Baesso, C; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, Th; Bay, A; Beddow, J; Bediaga, I; Belogurov, S; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carranza-Mejia, H; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Cauet, Ch; Charles, M; Charpentier, Ph; Chen, P; Chiapolini, N; Chrzaszcz, M; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Cogneras, E; Collins, P; Comerma-Montells, A; Contu, A; Contu, A; Cook, A; Coombes, M; Corti, G; Couturier, B; Cowan, G A; Craik, D; Cunliffe, S; Currie, R; D'Ambrosio, C; David, P; David, P N Y; De Bonis, I; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Del Buono, L; Deplano, C; Derkach, D; Deschamps, O; Dettori, F; Di Canto, A; Dickens, J; Dijkstra, H; Diniz Batista, P; Dogaru, M; Domingo Bonal, F; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Elsby, D; Falabella, A; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Ferguson, D; Fernandez Albor, V; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garosi, P; Garra Tico, J; Garrido, L; Gaspar, C; Gauld, R; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hampson, T; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; Harrison, P F; Hartmann, T; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hill, D; Hoballah, M; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Hussain, N; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kaballo, M; Kandybei, S; Karacson, M; Karbach, T M; Kenyon, I R; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Kochebina, O; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kucharczyk, M; Kudryavtsev, V; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Li, Y; Li Gioi, L; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; von Loeben, J; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Lu, H; Luisier, J; Luo, H; Mac Raighne, A; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Malde, S; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinelli, M; Martinez Santos, D; Martinez Santos, D; Martins Tostes, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Mazurov, A; McCarthy, J; McGregor, G; McNulty, R; Meier, F; Meissner, M; Merk, M; Merkel, J; Milanes, D A; Minard, M-N; Molina Rodriguez, J; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Muster, B; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nasteva, I; Needham, M; Neufeld, N; Nguyen, A D; Nguyen, T D; Nguyen-Mau, C; Nicol, M; Niess, V; Niet, R; Nikitin, N; Nikodem, T; Nomerotski, A; Novoselov, A; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B K; Palano, A; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C; Pazos Alvarez, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perego, D L; Perez Trigo, E; Pérez-Calero Yzquierdo, A; Perret, P; Perrin-Terrin, M; Pessina, G; Petridis, K; Petrolini, A; Phan, A; Picatoste Olloqui, E; Pie Valls, B; Pietrzyk, B; Pilař, T; Pinci, D; Playfer, S; Plo Casasus, M; Polci, F; Polok, G; Poluektov, A; Polycarpo, E; Popov, D; Popovici, B; Potterat, C; Powell, A; Prisciandaro, J; Pugatch, V; Puig Navarro, A; Qian, W; Rademacker, J H; Rakotomiaramanana, B; Rangel, M S; Raniuk, I; Rauschmayr, N; Raven, G; Redford, S; Reid, M M; dos Reis, A C; Ricciardi, S; Richards, A; Rinnert, K; Rives Molina, V; Roa Romero, D A; Robbe, P; Rodrigues, E; Rodrigues, E; Rodriguez Perez, P; Rogers, G J; Roiser, S; Romanovsky, V; Romero Vidal, A; Rouvinet, J; Ruf, T; Ruiz, H; Sabatino, G; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salzmann, C; Sanmartin Sedes, B; Sannino, M; Santacesaria, R; Santamarina Rios, C; Santinelli, R; Santovetti, E; Sapunov, M; Sarti, A; Satriano, C; Satta, A; Savrie, M; Savrina, D; Schaack, P; Schiller, M; Schindler, H; Schleich, S; Schlupp, M; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M-H; Schwemmer, R; Sciascia, B; Sciubba, A; Seco, M; Semennikov, A; Senderowska, K; Sepp, I; Serra, N; Serrano, J; Seyfert, P; Shapkin, M; Shapoval, I; Shatalov, P; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, O; Shevchenko, V; Shires, A; Silva Coutinho, R; Skwarnicki, T; Smith, N A; Smith, E; Smith, M; Sobczak, K; Soler, F J P; Soomro, F; Souza, D; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Stagni, F; Stahl, S; Steinkamp, O; Stoica, S; Stone, S; Storaci, B; Straticiuc, M; Straumann, U; Subbiah, V K; Swientek, S; Syropoulos, V; Szczekowski, M; Szczypka, P; Szumlak, T; T'Jampens, S; Teklishyn, M; Teodorescu, E; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Tolk, S; Tonelli, D; Topp-Joergensen, S; Torr, N; Tournefier, E; Tourneur, S; Tran, M T; Tresch, M; Tsaregorodtsev, A; Tsopelas, P; Tuning, N; Ubeda Garcia, M; Ukleja, A; Urner, D; Uwer, U; Vagnoni, V; Valenti, G; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; Velthuis, J J; Veltri, M; Veneziano, G; Vesterinen, M; Viaud, B; Videau, I; Vieira, D; Vilasis-Cardona, X; Visniakov, J; Vollhardt, A; Volyanskyy, D; Voong, D; Vorobyev, A; Vorobyev, V; Voß, C; Voss, H; Waldi, R; Wallace, R; Wandernoth, S; Wang, J; Ward, D R; Watson, N K; Webber, A D; Websdale, D; Whitehead, M; Wicht, J; Wiedner, D; Wiggers, L; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wishahi, J; Witek, M; Witzeling, W; Wotton, S A; Wright, S; Wu, S; Wyllie, K; Xie, Y; Xing, F; Xing, Z; Yang, Z; Young, R; Yuan, X; Yushchenko, O; Zangoli, M; Zavertyaev, M; Zhang, F; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhokhov, A; Zhong, L; Zvyagin, A

    2013-01-01

    The energy flow created in pp collisions at $\\sqrt{s}$=7 TeV is studied within the pseudorapidity range 1.9

  2. Comparison of models of high energy heavy ion collision. [0. 1 to 2. 0 GeV/nuo, review

    Energy Technology Data Exchange (ETDEWEB)

    Gyulassy, M.

    1977-10-01

    Some of the main theoretical developments on heavy ion collisions at energies (0.1 to 2.0) GeV/nuc are reviewed. The fireball, firestreak, hydrodynamic (1-fluid, 2-fluids), ''row on row'', hard sphere and intranuclear cascades, and classical equations of motion models are discussed in detail. Results are compared to each other and to measured Ne + U ..-->.. p + X reactions.

  3. Measurement of the forward energy flow in pp collisions at {radical}(s) = 7 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Aaij, R. [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands); Abellan Beteta, C. [Universitat de Barcelona, Barcelona (Spain); Adametz, A. [Ruprecht-Karls-Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany)] [and others; Collaboration: The LHCb Collaboration

    2013-05-15

    The energy flow created in pp collisions at {radical}(s) = 7 TeV is studied within the pseudorapidity range 1.9<{eta}<4.9 with data collected by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by Pythia-based and cosmic-ray event generators, which provide different models of soft hadronic interactions. (orig.)

  4. Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions

    CERN Document Server

    Vovchenko, V; Niemi, H; Karpenko, Iu A; Gorenstein, M I; Satarov, L M; Mishustin, I N; Kämpfer, B; Stoecker, H

    2016-01-01

    Partonic matter produced in the early stage of ultrarelativistic nucleus-nucleus collisions is assumed to be composed mainly of gluons, and quarks and antiquarks are produced at later times. The comparable hydrodynamic simulations of heavy-ion collisions for (2+1)-flavor and Yang-Mills equations of state performed by using three different hydrodynamic codes are presented. Assuming slow chemical equilibration of quarks, the spectra and elliptic flows of thermal dileptons and photons are calculated for central Pb+Pb collisions at the LHC energy of $\\sqrt{s_{_{\\rm NN}}} = 2.76$ TeV. It is shown that a suppression of quarks at early times leads to a significant reduction of the yield of the thermal dileptons, but only to a rather modest suppression of the $p_T$-distribution of direct photons. It is demonstrated that an enhancement of photon and dilepton elliptic flows might serve as a promising signature of the pure-glue initial state. Calculations based on Bjorken hydrodynamics suggest that collisions of small s...

  5. Multicomponent long-wave-short-wave resonance interaction system: Bright solitons, energy-sharing collisions, and resonant solitons.

    Science.gov (United States)

    Sakkaravarthi, K; Kanna, T; Vijayajayanthi, M; Lakshmanan, M

    2014-11-01

    We consider a general multicomponent (2+1)-dimensional long-wave-short-wave resonance interaction (LSRI) system with arbitrary nonlinearity coefficients, which describes the nonlinear resonance interaction of multiple short waves with a long wave in two spatial dimensions. The general multicomponent LSRI system is shown to be integrable by performing the Painlevé analysis. Then we construct the exact bright multisoliton solutions by applying the Hirota's bilinearization method and study the propagation and collision dynamics of bright solitons in detail. Particularly, we investigate the head-on and overtaking collisions of bright solitons and explore two types of energy-sharing collisions as well as standard elastic collision. We have also corroborated the obtained analytical one-soliton solution by direct numerical simulation. Also, we discuss the formation and dynamics of resonant solitons. Interestingly, we demonstrate the formation of resonant solitons admitting breather-like (localized periodic pulse train) structure and also large amplitude localized structures akin to rogue waves coexisting with solitons. For completeness, we have also obtained dark one- and two-soliton solutions and studied their dynamics briefly.

  6. Statistical model analysis of hadron yields in proton-nucleus and heavy-ion collisions at SIS 18 energies

    CERN Document Server

    Agakishiev, G; Balanda, A; Belver, D; Belyaev, A; Berger-Chen, J C; Blanco, A; Böhmer, M; Boyard, J L; Cabanelas, P; Castro, E; Chernenko, S; Destefanis, M; Dohrmann, F; Dybczak, A; Epple, E; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, P; Friese, J; Fröhlich, I; Galatyuk, T; Garzon, J A; Gernhäuser, R; Gilardi, C; Göbel, K; Golubeva, M; Gonzalez-Diaz, D; Guber, F; Gumberidze, M; Heinz, T; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kämpfer, B; Karavicheva, T; Koenig, I; Koenig, W; Kolb, B W; Kornakov, G; Kotte, R; Krasa, A; Krizek, F; Krücken, R; Kuc, H; Kühn, W; Kugler, A; Kurepin, A; Ladygin, V; Lalik, R; Lange, J S; Lang, S; Lapidus, K; Lebedev, A; Liu, T; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Markert, J; Metag, V; Michalska, B; Michel, J; Moriniere, E; Mousa, J; Müntz, C; Münzer, R; Naumann, L; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Pietraszko, J; Przygoda, W; Ramstein, B; Rehnisch, L; Reshetin, A; Rustamov, A; Sadovsky, A; Salabura, P; Scheib, T; Schmah, A; Schuldes, H; Schwab, E; Siebenson, J; Sobolev, Yu G; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Tarantola, A; Teilab, K; Tlusty, P; Traxler, M; Trebacz, R; Tsertos, H; Vasiliev, T; Wagner, V; Weber, M; Wendisch, C; Wisniowski, M; Wüstenfeld, J; Yurevich, S; Zanevsky, Y

    2015-01-01

    The HADES data from p+Nb collisions at center of mass energy of $\\sqrt{s_{NN}}$= 3.2 GeV are analyzed by employing a statistical model. Accounting for the identified hadrons $\\pi^0$, $\\eta$, $\\Lambda$, $K^{0}_{s}$, $\\omega$ allows a surprisingly good description of their abundances with parameters $T_{chem}=(99\\pm11)$ MeV and $\\mu_{b}=(619\\pm34)$ MeV, which fits well in the chemical freeze-out systematics found in heavy-ion collisions. In supplement we reanalyze our previous HADES data from Ar+KCl collisions at $\\sqrt{s_{NN}}$= 2.6 GeV with an updated version of the statistical model. We address equilibration in heavy-ion collisions by testing two aspects: the description of yields and the regularity of freeze-out parameters from a statistical model fit. Special emphasis is put on feed-down contributions from higher-lying resonance states which have been proposed to explain the experimentally observed $\\Xi^-$ excess present in both data samples.

  7. Searching for onset of quark deconfinement and critical point of QGP phase transition from rapidity distribution in high energy collisions

    CERN Document Server

    Liu, Fu-Hu; Lacey, Roy A

    2015-01-01

    Experimental results of the rapidity distributions of negatively charged pions produced in proton-proton (p-p) and beryllium-beryllium (Be-Be) collisions at different beam momentums, measured by the NA61/SHINE Collaboration at the super proton synchrotron (SPS), are described by a revised (three-source) Landau hydrodynamic model. The squared speed-of-sound parameter c^2_s is then extracted from the width of rapidity distribution. There is a knee point appearing at about 40A GeV/c (or 8.8 GeV) in the dependence of c^2_s on incident beam momentum (or center-of-mass energy). This knee point can be possibly regarded as the onset of deconfinement of the quarks and gluons in proton-proton collisions, and the critical point of phase transition from hadronic matter to quark-gluon plasma (QGP) in nucleus-nucleus collisions. It is possible that the quark deconfinement and QGP phase transition happen initially in collisions at 8.8 GeV.

  8. Energy dependence of pi-zero production in Cu+Cu collisions at sqrt(s_NN) = 22.4, 62.4, and 200 GeV

    CERN Document Server

    Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Asai, J; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Baldisseri, Alberto; Barish, K N; Barnes, P D; Bassalleck, B; Basye, A T; Bathe, S; Batsouli, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Büsching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chang, B S; Chang, W C; Charvet, J L; Chernichenko, S; Chiba, J; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Chujo, T; Chung, P; Churyn, A; Cianciolo, V; Citron, Z; Cleven, C R; Cole, B A; Comets, M P; Constantin, P; Csanad, M; Csrgo, T; Dahms, T; Dairaku, S; Das, K; Dávid, G; Deaton, M B; Dehmelt, K; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Dubey, A K; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Yu V; Egdemir, J; Ellinghaus, F; Emam, W S; Engelmore, T; Enokizono, A; Enyo, H; Esumi, S; Eyser, K O; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Zeev; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gadrat, S; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse-Perdekamp, M; Gunji, T; Gustafsson, H; Hachiya, T; Hadj Henni, A; Haegemann, C; Haggerty, J S; Hamagaki, H; Han, AR; Harada, H; Hartouni, E P; Haruna, K; Haslum, E; Hayano, R; Heffner, M; Hemmick, T K; Hester, T; He, X; Hiejima, H; Hill, J C; Hobbs, R; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ikeda, Y; Imai, K; Imrek, J; Inaba, M; Inoue, Y; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kaneta, M; Kang, J H; Kanou, H; Kapustinsky, J; Kawall, D; Kazantsev, A V; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, S H; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Kiyomichi, A; Klay, J; Klein-Bösing, C; Kochenda, L; Kochetkov, V; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Krl, A; Kravitz, A; Kubart, J; Kunde, G J; Kurihara, N; Kurita, K; Kurosawa, M; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lai, Y S; Lajoie, J G; Layton, D; Lebedev, A; Lee, D M; Lee, K B; Lee, M K; Lee, T; Leitch, M J; Leite, M A L; Lenzi, B; Liebing, P; Lika, T; Litvinenko, A; Liu, H; Liu, M X; Li, X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Man'ko, V I; Mannel, E; Mao, Y; Maek, L; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mike, P; Miki, K; Miller, T E; Milov, A; Mioduszewski, S; Mishra, M; Mitchell, J T; Mitrovski, M; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Mukhopadhyay, D; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Niita, T; Norman, B E; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Ohnishi, H; Okada, H; Okada, K; Oka, M; Omiwade, O O; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Peng, J C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Rembeczki, S; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roach, D; Roche, G; Rolnick, S D; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ruika, P; Rykov, V L; Sahlmueller, B; Saitô, N; Sakaguchi, T; Sakai, S; Sakashita, K; Sakata, H; Samsonov, V; Sato, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Semenov, V; Seto, R; Sharma, D; Shein, I; Shevel, A; Shibata, T A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Skutnik, S; Sluneka, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sørensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sukhanov, A; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarjn, P; Themann, H; Thomas, T L; Togawa, M; Toia, A; Tojo, J; Tomaek, L; Tomita, Y; Torii, H; Towell, R S; Tram, V-N; Tserruya, Itzhak; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Veicht, A; Velkovska, J; Vertesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wagner, M; Walker, D; Wang, X R; Watanabe, Y

    2008-01-01

    Neutral pion transverse momentum (pT) spectra at mid-rapidity (|y| < 0.35) were measured in Cu+Cu collisions at \\sqrt s_NN = 22.4, 62.4, and 200 GeV. Relative to pi -zero yields in p+p collisions scaled by the number of inelastic nucleon-nucleon collisions (Ncoll) at the respective energies, the pi-zero yields for pT \\ge 2 GeV/c in central Cu+Cu collisions at 62.4 and 200 GeV are suppressed, whereas an enhancement is observed at 22.4 GeV. A comparison with a jet quenching model suggests that final state parton energy loss dominates in central Cu+Cu collisions at 62.4 GeV and 200 GeV, while the enhancement at 22.4 GeV is consistent with nuclear modifications in the initial state alone.

  9. A description of the pseudorapidity distributions in heavy ion collisions at RHIC and LHC energies

    CERN Document Server

    Jiang, Z J; Zhang, H L; Deng, H P

    2015-01-01

    The charged particles produced in nucleus-nucleus collisions are classified into two parts,One is from the hot and dense matter created in collisions. The other is from leading particles. The hot and dense matter is assumed to expand and generate particles according to BJP hydrodynamics, a theory put forward by A. Bialas, R. A. Janik and R. Peschanski. The leading particles are argued to possess a Gaussian rapidity distribution with the normalization constant equaling the number of participants. A comparison is made between the theoretical results and the experimental measurements performed by BRAHMS and PHOBOS Collaboration at BNL-RHIC in Au-Au and Cu-Cu collisions at sqrt(s_NN)=200 GeV and by ALICE Collaboration at CERN-LHC in Pb-Pb collisions at sqrt(s_NN) =2.76 TeV. The theoretical results are well consistent with experimental data.

  10. A description of the pseudorapidity distributions in heavy ion collisions at RHIC and LHC energies

    Science.gov (United States)

    Jiang, Z. J.; Zhang, Y.; Zhang, H. L.; Deng, H. P.

    2015-09-01

    The charged particles produced in nucleus-nucleus collisions are classified into two parts: One is from the hot and dense matter created in collisions. The other is from leading particles. The hot and dense matter is assumed to expand and generate particles according to BJP hydrodynamics, a theory put forward by A. Bialas, R.A. Janik and R. Peschanski. The leading particles are argued to possess a Gaussian rapidity distribution with the normalization constant equaling the number of participants. A comparison is made between the theoretical results and the experimental measurements performed by BRAHMS and PHOBOS Collaborations at BNL-RHIC in Au-Au and Cu-Cu collisions at √{sNN} = 200 GeV and by ALICE Collaboration at CERN-LHC in Pb-Pb collisions at √{sNN} = 2.76 TeV. The theoretical results are well consistent with experimental data.

  11. High Resolution Crossed Molecular Beams Study on the F+HD→HF+D Reaction at Collision Energy of 5.43-18.73 kJ/mol

    Institute of Scientific and Technical Information of China (English)

    Wen-rui Dong; Chun-lei Xiao; Tao Wang; Dong-xu Dai; Xiu-yan Wang; Xue-ming Yang

    2011-01-01

    The dynamics of F+HD→HF+D reaction has been studied at ten collision energies ranging from 5.43 kJ/mol to 18.73 kJ/mol using high-resolution H/D atom Rydberg tagging time-of-flight method.Product vibrational and rotational state-resolved differential cross sections have been determined.The intensity of the HF(v'=2) forward products decreases as the collision energy increases,suggesting that the resonance contribution is reduced as the collision energy increases.The forward peak of HF(v'=3) product has also been observed above the threshold of this product channel.Product energy disposals in different degrees of freedom have been analyzed.The collision energy dependence of the HF vibrational product branching was also determined.This work presents a comprehensive dynamic picture of this resonance mediated reaction in a wide collision energy regime,providing a good test ground for theoretical understandings of this interesting reaction at higher collision energies.

  12. Proton and neutron density distributions at supranormal density in low- and medium-energy heavy-ion collisions

    Science.gov (United States)

    Stone, J. R.; Danielewicz, P.; Iwata, Y.

    2017-07-01

    Background: The distribution of protons and neutrons in the matter created in heavy-ion collisions is one of the main points of interest for the collision physics, especially at supranormal densities. These distributions are the basis for predictions of the density dependence of the symmetry energy and the density range that can be achieved in a given colliding system. We report results of the first systematic simulation of proton and neutron density distributions in central heavy-ion collisions within the beam energy range of Ebeam≤800 MeV /nucl . The symmetric 40Ca+40Ca , 48Ca+48Ca , 100Sn+100Sn , and 120Sn+120Sn and asymmetric 40Ca+48Ca and 100Sn+120Sn systems were chosen for the simulations. Purpose: We simulate development of proton and neutron densities and asymmetries as a function of initial state, beam energy, and system size in the selected collisions in order to guide further experiments pursuing the density dependence of the symmetry energy. Methods: The Boltzmann-Uhlenbeck-Uehling (pBUU) transport model with four empirical models for the density dependence of the symmetry energy was employed. Results of simulations using pure Vlasov dynamics were added for completeness. In addition, the time-dependent Hartree-Fock (TDHF) model, with the SV-bas Skyrme interaction, was used to model the heavy-ion collisions at Ebeam≤40 MeV /nucl . Maximum proton and neutron densities ρpmax and ρnmax, reached in the course of a collision, were determined from the time evolution of ρp and ρn. Results: The highest total densities predicted at Ebeam=800 MeV /nucl . were of the order of ˜2.5 ρ0 (ρ0=0.16 fm-3 ) for both Sn and Ca systems. They were found to be only weakly dependent on the initial conditions, beam energy, system size, and a model of the symmetry energy. The proton-neutron asymmetry δ =(ρnmax-ρpmax) /(ρnmax+ρpmax) at maximum density does depend, though, on these parameters. The highest value of δ found in all systems and at all investigated beam

  13. Measurement of the Transverse Energy Spectrum in Proton-Nucleon Collisions.

    Science.gov (United States)

    Bettoni, Diego

    We describe a measurement of the transverse energy spectrum in proton-nucleon interactions carried out at the CERN SPS using the HELIOS spectrometer. The measurement is of particular interest in that it is performed in a rapidity region away from central rapidity, where experimental data is scarce. In this rapidity region very interesting physics is anticipated and the measurement of the proton -nucleon collisions is essential as a basis to understand the more complicated proton-nucleus and nucleus-nucleus interactions. Both these topics are part of the experimental programme of HELIOS. The measurement was done using a deuterium target enclosed in an iron tube. The contribution to the transverse energy spectrum from the p-Fe events is discriminated against by reconstructing the primary interaction vertex using drift chamber information. The measured spectrum is corrected via Monte Carlo to deconvolute the effect of reinteractions. We also report, in the first part of the thesis, on the author's contribution to the development of the high-resolution drift chambers employed in the HELIOS detector. High spatial resolution and multi-track resolving power are achieved with the use of a cool gas, such that the electron characteristic energy is close to the thermal limit: this implies a small diffusion coefficient and a consequently good positional accuracy. Of vital importance are the low value of the drift velocity, the fast, differentiating electronics and a careful shaping of the electric field configuration to improve the isochrony of the drift collection. We report on the design and tests of drift chamber prototypes built along the above lines, with which a spatial accuracy of 0.06 mm and a double track resolution of 0.6 mm were measured. We also describe the final drift chamber system and its operation in HELIOS, and we point out the great care with which all systematic effects must be kept under control. The author's personal contribution to this work has been the

  14. Event-by-event distribution of magnetic field energy over initial fluid energy density in $\\sqrt{s_{\\rm NN}}$= 200 GeV Au-Au collisions

    CERN Document Server

    Roy, Victor

    2015-01-01

    We estimate the event-by-event (e-by-e) distribution of the ratio ($\\sigma$) of the magnetic field energy to the fluid energy density in the transverse plane of Au-Au collisions at $\\sqrt{s_{\\rm NN}}$ = 200 GeV. A Monte-Carlo (MC) Glauber model is used to calculate the $\\sigma$ in the transverse plane for impact parameter b=0, 12 fm at time $\\tau_i\\sim$0.5 fm. The fluid energy density is obtained by using Gaussian smoothing with two different smoothing parameter $\\sigma_g$=0.25 , 0.5 fm. For $b=0~\\rm fm$ collisions $\\sigma$ is found to be $\\ll$ 1 in the central region of the fireball and $\\sigma\\gtrsim$ 1 at the periphery. For b=12 fm collisions $\\sigma\\gtrsim$ 1. The e-by-e correlation between $\\sigma$ and the fluid energy density ($\\varepsilon$) is studied. We did not find strong correlation between $\\sigma$ and $\\varepsilon$ at the centre of the fireball, whereas they are mostly anti-correlated at the periphery of the fireball.

  15. Design and performance simulation of a segmented-absorber based muon detection system for high energy heavy ion collision experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, S. [University of Kashmir, Srinagar (India); Bhaduri, P.P. [Variable Energy Cyclotron Centre, Kolkata (India); Jahan, H. [Aligarh Muslim University, Aligarh (India); Senger, A. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Adak, R.; Samanta, S. [Bose Institute, Kolkata (India); Prakash, A. [Banaras Hindu University, Varanasi (India); Dey, K. [Gauhati University, Guwahati (India); Lebedev, A. [Institute für Kernphysik, Goethe Universität Frankfurt, Frankfurt (Germany); Kryshen, E. [Petersburg Nuclear Physics Institute (PNPI) NRC Kurchatov Institute, Gatchina (Russian Federation); Chattopadhyay, S., E-mail: sub@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India); Senger, P. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Bhattacharjee, B. [Gauhati University, Guwahati (India); Ghosh, S.K.; Raha, S. [Bose Institute, Kolkata (India); Irfan, M.; Ahmad, N. [Aligarh Muslim University, Aligarh (India); Farooq, M. [University of Kashmir, Srinagar (India); Singh, B. [Banaras Hindu University, Varanasi (India)

    2015-03-01

    A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)

  16. Scattering of NH{sub 3} and ND{sub 3} with rare gas atoms at low collision energy

    Energy Technology Data Exchange (ETDEWEB)

    Loreau, J., E-mail: jloreau@ulb.ac.be [Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles (ULB) CP 160/09, 50 av. F.D. Roosevelt, 1050 Brussels (Belgium); Avoird, A. van der, E-mail: A.vanderAvoird@theochem.ru.nl [Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands)

    2015-11-14

    We present a theoretical study of elastic and rotationally inelastic collisions of NH{sub 3} and ND{sub 3} with rare gas atoms (He, Ne, Ar, Kr, Xe) at low energy. Quantum close-coupling calculations have been performed for energies between 0.001 and 300 cm{sup −1}. We focus on collisions in which NH{sub 3} is initially in the upper state of the inversion doublet with j = 1, k = 1, which is the most relevant in an experimental context as it can be trapped electrostatically and Stark-decelerated. We discuss the presence of resonances in the elastic and inelastic cross sections, as well as the trends in the inelastic cross sections along the rare gas series and the differences between NH{sub 3} and ND{sub 3} as a colliding partner. We also demonstrate the importance of explicitly taking into account the umbrella (inversion) motion of NH{sub 3} in order to obtain accurate scattering cross sections at low collision energy. Finally, we investigate the possibility of sympathetic cooling of ammonia using cold or ultracold rare gas atoms. We show that some systems exhibit a large ratio of elastic to inelastic cross sections in the cold regime, which is promising for sympathetic cooling experiments. The close-coupling calculations are based on previously reported ab initio potential energy surfaces for NH{sub 3}–He and NH{sub 3}–Ar, as well as on new, four-dimensional, potential energy surfaces for the interaction of ammonia with Ne, Kr, and Xe, which were computed using the coupled-cluster method and large basis sets. We compare the properties of the potential energy surfaces corresponding to the interaction of ammonia with the various rare gas atoms.

  17. Effective collision strengths for excitation and de-excitation of nebular [O III] optical and infrared lines with kappa distributed electron energies

    CERN Document Server

    Storey, P J

    2015-01-01

    We present effective collision strengths for electron excitation and de-excitation of the ten forbidden transitions between the five lowest energy levels of the astronomically abundant doubly-ionised oxygen ion, O^{2+}. The raw collision strength data were obtained from an R-matrix intermediate coupling calculation using the Breit-Pauli relativistic approximation published previously by the authors. The effective collision strengths were calculated with kappa-distributed electron energies and are tabulated as a function of the electron temperature and kappa.

  18. High baryon densities in heavy ion collisions at energies attainable at the BNL Relativistic Heavy-Ion Collider and the CERN Large Hadron Collider

    Science.gov (United States)

    Li, Ming; Kapusta, Joseph I.

    2017-01-01

    In very high-energy collisions nuclei are practically transparent to each other but produce very hot nearly baryon-free matter in the so-called central rapidity region. The energy in the central rapidity region comes from the kinetic energy of the colliding nuclei. We calculate the energy and rapidity loss of the nuclei using the color glass condensate model. This model also predicts the excitation energy of the nuclear fragments. Using a space-time picture of the collision we calculate the baryon and energy densities of the receding baryonic fireballs. For central collisions of gold nuclei at the highest energy attainable at the Relativistic Heavy-Ion Collider, for example, we find baryon densities more than ten times that of atomic nuclei over a large volume.

  19. High Baryon Densities in Heavy Ion Collisions at Energies Attainable at the Relativistic Heavy Ion Collider and the Large Hadron Collider

    CERN Document Server

    Li, Ming

    2016-01-01

    In very high energy collisions nuclei are practically tranparent to each other but produce very hot, nearly baryon-free, matter in the so-called central rapidity region. The energy in the central rapidity region comes from the kinetic energy of the colliding nuclei. We calculate the energy and rapidity loss of the nuclei using the color glass condensate model. This model also predicts the excitation energy of the nuclear fragments. Using a space-time picture of the collision we calculate the baryon and energy densities of the receding baryonic fireballs. For central collisions of gold nuclei at the highest energy attainable at the Relativistic Heavy Ion Collider, for example, we find baryon densities more than ten times that of atomic nuclei over a large volume.

  20. Light Hadron Production in Proton-Proton Collisions at Different LHC Energies: Measured Data versus a Model

    CERN Document Server

    Guptaroy, P

    2014-01-01

    Experiments involving proton-proton collisions at energies $\\sqrt{s_{NN}}$ = 0.9, 2.76 and 7 TeV in Large Hadron Collider (LHC) have produced a vast amount of high-precision data. Here, in this work, we have chosen to analyse the two aspects of the measured data, viz., (i) the $p_T$ -spectra of pions, kaons, proton-antiproton at above-mentioned energies, and (ii) some of their very important ratio-behaviours, in the light of a version of the Sequential Chain Model (SCM). The agreements between the measured data and model-based results are generally found to be modestly satisfactory.

  1. Charge Dependence and Electric Quadrupole Effects on Single-Nucleon Removal in Relativistic and Intermediate Energy Nuclear Collisions

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.

  2. Charge Dependence and Electric Quadrupole Effects on Single-Nucleon Removal in Relativistic and Intermediate Energy Nuclear Collisions

    Science.gov (United States)

    Norbury, John W.

    1992-01-01

    Single nucleon removal in relativistic and intermediate energy nucleus-nucleus collisions is studied using a generalization of Weizsacker-Williams theory that treats each electromagnetic multipole separately. Calculations are presented for electric dipole and quadrupole excitations and incorporate a realistic minimum impact parameter, Coulomb recoil corrections, and the uncertainties in the input photonuclear data. Discrepancies are discussed. The maximum quadrupole effect to be observed in future experiments is estimated and also an analysis of the charge dependence of the electromagnetic cross sections down to energies as low as 100 MeV/nucleon is made.

  3. Top-quark production in proton-nucleus and nucleus-nucleus collisions at LHC energies and beyond

    CERN Document Server

    d'Enterria, David; Paukkunen, Hannu

    2015-01-01

    Single and pair top-quark production in proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions at the CERN Large Hadron Collider (LHC) and future circular collider (FCC) energies, are studied with next-to-leading-order perturbative QCD calculations including nuclear parton distribution functions. At the LHC, the pair-production cross sections amount to sigma(t-tbar) = 3.4 mub in Pb-Pb at sqrt(s) = 5.5 TeV, and sigma(t-tbar) = 60 nb in p-Pb at sqrt(s) = 8.8 TeV. At the FCC energies of sqrt(s) = 39 and 63 TeV, the same cross sections are factors of 90 and 55 times larger respectively. In the leptonic final-state t-tbar --> W+b W-bbar --> b bbar l+l- nu+nu-, after typical acceptance and efficiency cuts, one expects about 90 and 300 top-quarks per nominal LHC-year and 4.7 10^4 and 10^5 per FCC-year in Pb-Pb and p-Pb collisions respectively. The total t-tbar cross sections, dominated by gluon fusion processes, are enhanced by 3--8% in nuclear compared to p-p collisions due to an overall net gluon antishadowing, altho...

  4. Study Of Open Charm Production In Proton+proton Collisions At Center Of Mass Energies = 200 Gev

    CERN Document Server

    Butsyk, S

    2005-01-01

    The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) with its unique electron identification system enables us to perform high precision measurements of electron yields. By measuring electron production at high transverse momentum, we can disentangle the contribution of electrons originating from semi-leptonic decays of heavy quarks (charm or bottom) from the less interesting “photonic” decay modes of light mesons. D/B mesons carry single heavy valence quarks and are usually referred to as “Open Charm” and “Open Bottom” particles, differentiating them from Closed Flavor particles such as J/ψ, and Y mesons. Due to the large mass of the heavy quarks, their production mechanisms can be adequately explained by perturbative QCD (pQCD) theory. This dissertation presents the measurement of electrons from heavy flavor decays in proton + proton collisions at RHIC at collision energy s = 200 GeV over a wide range of transverse momen...

  5. Experimental testing of ab initio potential energy surfaces: Stereodynamics of NO(A(2)Σ(+)) + Ne inelastic scattering at multiple collision energies.

    Science.gov (United States)

    Luxford, Thomas F M; Sharples, Thomas R; McKendrick, Kenneth G; Costen, Matthew L

    2016-11-07

    We present a crossed molecular beam velocity-map ion imaging study of state-to-state rotational energy transfer of NO(A(2)Σ(+), v = 0, N = 0, j = 0.5) in collisions with Ne atoms. From these measurements, we report differential cross sections and angle-resolved rotational angular momentum alignment moments for product states N' = 3 and 5-10 for collisions at an average energy of 523 cm(-1), and N' = 3 and 5-14 for collisions at an average energy of 1309 cm(-1), respectively. The experimental results are compared to the results of close-coupled quantum scattering calculations on two literature ab initio potential energy surfaces (PESs) [Pajón-Suárez et al., Chem. Phys. Lett. 429, 389 (2006) and Cybulski and Fernández, J. Phys. Chem. A 116, 7319 (2012)]. The differential cross sections from both experiment and theory show clear rotational rainbow structures at both collision energies, and comparison of the angles observed for the rainbow peaks leads to the conclusion that Cybulski and Fernández PES better represents the NO(A(2)Σ(+))-Ne interaction at the collision energies used here. Sharp, forward scattered (theory on either PES. We identify these as L-type rainbows, characteristic of attractive interactions, and consistent with a shallow well in the collinear Ne-N-O geometry, similar to that calculated for the NO(A(2)Σ(+))-Ar surface [Kłos et al., J. Chem. Phys. 129, 244303 (2008)], but absent from both of the NO(A(2)Σ(+))-Ne surfaces tested here. The angle-resolved alignment moments calculated by quantum scattering theory are generally in good agreement with the experimental results, but both experiment and quantum scattering theories are dramatically different to the predictions of a classical rigid-shell, kinematic-apse conservation model. Strong oscillations are resolved in the experimental alignment moments as a function of scattering angle, confirming and extending the preliminary report of this behavior [Steill et al., J. Phys. Chem. A 117, 8163

  6. A combined model for pseudorapidity distributions in Cu-Cu collisions at BNL-RHIC energies

    CERN Document Server

    Jiang, Zhjin; Huang, Yan

    2016-01-01

    The charged particles produced in nucleus-nucleus collisions come from leading particles and those frozen out from the hot and dense matter created in collisions. The leading particles are conventionally supposed having Gaussian rapidity distributions normalized to the number of participants. The hot and dense matter is assumed to expand according to the unified hydrodynamics, a hydro model which unifies the features of Landau and Hwa-Bjorken model, and freeze out into charged particles from a space-like hypersurface with a proper time of Tau_FO . The rapidity distribution of this part of charged particles can be derived out analytically. The combined contribution from both leading particles and unified hydrodynamics is then compared against the experimental data performed by BNL-RHIC-PHOBOS Collaboration in different centrality Cu-Cu collisions at sqrt(s_NN)=200 and 62.4 GeV, respectively. The model predictions are in well consistent with experimental measurements.

  7. Trajectory-dependent energy- and charge-transfer in collisions of Br sup + ( sup 3 P sub 2) with Pt(1 1 1)

    CERN Document Server

    Maazouz, P L; Jacobs, D C

    2003-01-01

    Collisions of hyperthermal energy Br sup + ( sup 3 P sub 2) with Pt(1 1 1) produces scattered Br sup - ( sup 1 S sub 0) with a yield approaching 7%. The energy distribution of the scattered product exhibits an unusual dependence on the collision energy. Specifically, as the incident energy increases from 34 to 54 eV, the peak energy of scattered Br sup - ( sup 1 S sub 0) decreases. Furthermore, the anion yield reaches a sharp maximum when Br sup + ( sup 3 P sub 2) approaches the surface with 26 eV of translational energy. The unusual scattering behavior is attributed to a trajectory dependent collision-induced deformation of the lattice. The corresponding electronic perturbation evolves synchronously with the motion of the departing projectile - leading to an enhanced charge-transfer probability.

  8. Thermal Bremsstrahlung probing nuclear multifragmentation in nucleus-nucleus collisions around the Fermi energy; Bremsstrahlung thermique comme sonde de la multifragmentation nucleaire dans les collisions noyau-noyau aux energies de Fermi

    Energy Technology Data Exchange (ETDEWEB)

    D' Enterria, D.G

    2000-05-15

    The thermodynamical properties of nuclear matter at moderate temperatures and densities, in the vicinity of the predicted nuclear liquid-gas phase transition, are studied using as experimental probe the hard-photons (E{sub {gamma}} > 30 MeV) emitted in nucleus-nucleus collisions. Photon and charged-particle production in four different heavy-ion reactions (Ar{sup 36} + Au{sup 197}, Ag{sup 107}, Ni{sup 58}, C{sup 12} at 60 A*MeV) is measured exclusively and inclusively coupling the TAPS photon spectrometer with two charged-particle and intermediate-mass-fragment detectors covering nearly 4{pi}. We confirm that Bremsstrahlung emission in first-chance (off-equilibrium) proton-neutron collisions (pn{gamma}) is the dominant origin of hard photons. We also firmly establish the existence of a thermal radiation component emitted in second-chance proton-neutron collisions. This thermal Bremsstrahlung emission takes place in semi-central and central nucleus-nucleus reactions involving heavy targets. We exploit this observation i) to demonstrate that thermal equilibrium is reached during the reaction, ii) to establish a new thermometer of nuclear matter based on Bremsstrahlung photons, iii) to derive the thermodynamical properties of the excited nuclear sources and, in particular, to establish a 'caloric curve' (temperature versus excitation energy), and iv) to assess the time-scales of the nuclear break-up process. (author)

  9. Ion acoustic kinetic Alfvén rogue waves in two temperature electrons superthermal plasmas

    Science.gov (United States)

    Kaur, Nimardeep; Saini, N. S.

    2016-10-01

    The propagation properties of ion acoustic kinetic Alfvén (IAKA) solitary and rogue waves have been investigated in two temperature electrons magnetized superthermal plasma in the presence of dust impurity. A nonlinear analysis is carried out to derive the Korteweg-de Vries (KdV) equation using the reductive perturbation method (RPM) describing the evolution of solitary waves. The effect of various plasma parameters on the characteristics of the IAKA solitary waves is studied. The dynamics of ion acoustic kinetic Alfvén rogue waves (IAKARWs) are also studied by transforming the KdV equation into nonlinear Schrödinger (NLS) equation. The characteristics of rogue wave profile under the influence of various plasma parameters (κc, μc, σ , θ) are examined numerically by using the data of Saturn's magnetosphere (Schippers et al. 2008; Sakai et al. 2013).

  10. Photon production in relativistic nuclear collisions at SPS and RHIC energies

    CERN Document Server

    Turbide, S; Rapp, R; 10.1142/S0217751X0402258X

    2004-01-01

    Chiral Lagrangians are used to compute the production rate of photons from the hadronic phase of relativistic nuclear collisions. Special attention is paid to the role of the a/sub 1/ pseudovector. Calculations that include strange meson reactions, form factors, the use of consistent vector spectral densities, the emission from a quark-gluon plasma, and primordial nucleon-nucleon collisions reproduce the photon spectra measured at the Super Proton Synchrotron (SPS). Some predictions for the Relativistic Heavy Ion Collider (RHIC) are made.

  11. High energy Pb+Pb collisions as seen by the NA44 experiment

    CERN Document Server

    Hardtke, D; Bøggild, H; Boissevain, J G; Dodd, J; Erazmus, B; Esumi, S C; Fabjan, Christian Wolfgang; Ferenc, D; Fields, D E; Franz, A; Gaardhøje, J J; Hamelin, M; Hansen, A G; Hansen, O; Hardtke, D; van Hecke, H; Holzer, E B; Humanic, T J; Hummel, P; Jacak, B V; Jayanti, R; Kaimi, K; Kanata, M; Kohama, T; Kopytine, M L; Leltchouk, M; Ljubicic, A; Lörstad, B; Maeda, N; Malina, R; Medvedev, A; Murray, M; Ohnishi, H; Paic, G; Pandey, S U; Piuz, François; Pluta, J; Polychronakos, V; Potekhin, M V; Poulard, G; Reichhold, D M; Sakaguchi, A; Simon-Gillo, J; Schmidt-Sørensen, J; Sondheim, W E; Spegel, M; Sugitate, T; Sullivan, J P; Sumi, Y; Willis, W J; Wolf, K L; Xu, N; Zachary, D S

    1999-01-01

    NA44 is a focusing spectrometer at the CERN SPS that measures single- particle inclusive spectra and two-particle correlations near mid- rapidity. Recent data taken using a 158 GeV/nucleon Pb beam incident on a Pb target will be presented. These data will be compared to data taken using other projectile-target combinations. The data show that the emission volume in Pb+Pb collisions is larger than in lighter projectile-target systems, that a large degree of collective radial flow is created in these collisions, and that different particle species probe different regions of the freeze-out volume. (22 refs).

  12. Lectures on the Near-Side Ridge, Landau Hydrodynamics, and Heavy Quarkonia in High Energy Heavy-Ion Collisions

    Directory of Open Access Journals (Sweden)

    Wong C.-Y.

    2010-10-01

    Full Text Available We give an introduction to three different topics that are of current interest in heavy-ion collisions. Particles associated with the near-side jet are found to exhibit a Δφ-Δη correlation in the form of a ridge in the Δη direction but a peak at Δφ ~ 0. The experimental data support the description that the ridge particles are medium partons kicked by the jet. The measurement of the characteristics of the ridge provides a unique tool to probe the nature of the (jet parton-(medium parton collision and the momentum distribution of dense matter formed in the early stage of the heavy-ion collision. We find that the magnitude of the longitudinal momentum kick along the jet direction acquired by a medium parton in collision with the jet is about 1 GeV, and the early parton momentum distribution is in the form of a rapidity plateau with a thermal-type transverse momentum distribution. In the second lecture, we re-examine the validity of Landau hydrodynamics which provides a reasonable description of the space-time dynamics of the hot matter produced in high-energy heavy-ion collisions. We find that the rapidity distribution of produced particles should be more appropriately modified from Landau’s result. Past successes of the Gaussian distribution in explaining experimental rapidity data can be understood, not because it is an approximation of the original Landau distribution, but because it is in fact a close representation of the modified distribution. In the final lecture, we give an introduction to the development of the potential model for quarkonia, using thermodynamical quantities obtained in lattice gauge calculations. We find that the potential model is consistent with the lattice gauge spectral function analysis, if the color-singlet heavy quark-antiquark potential is a linear combination of the color-singlet free energy F1 and internal energy U1 , with coefficients that depend on the equation of state. We find that the e

  13. Dust acoustic double layers in a magnetized dusty self-gravitating plasma with superthermal particles

    Science.gov (United States)

    Sabetkar, Akbar; Dorranian, Davoud

    2016-08-01

    Our prime objective of this paper is to examine the parametric regimes for the existence and polarity of dust acoustic double layers (DADLs) and its solitary structures arising from a magnetized self-gravitating opposite polarity dust-plasma (OPDP) model. The constituents of the OPDP model are two species of positively and negatively charged dust grains, Maxwellian electrons and kappa distributed ions. Contributions of gravitational force only on dust grains are taken into account. For weakly nonlinear analysis, the multiple time scale technique has been used to construct the extended Korteweg-de Vries (E-KdV) and modified Korteweg-de Vries (M-KdV) equations. They pinpoint the evolution of DADLs and solitary structures associated with dust acoustic (DA) mode, respectively. The relevant configurational parameters in our study include the superthermality of ions (κ), obliqueness of propagation (θ), ion concentration (δi), static magnetic field B0 (via ω c p , ω c n ), and self-gravitational field (via γ), as well as the density (μ0), charge (α), and mass (β) ratio of positive to negative dust species. The proposed OPDP model permits positive and negative double layer polarities, while higher order nonlinear equation dictates us only positive polarity solitary structures. The main modification due to an increase in self-gravitational field (via γ) is an enhancement in the spatial width of double layers, yet leaving their amplitude, phase speed, and polarity practically unaffected. With enhanced superthermality and other intrinsic parameters in OPDP model, there is an opposite trend in both amplitude and width of double layers, while the amplitude and the width of solitary waves (via M-KdV equation) undergo the identical behaviors. In particular, the amplitude of solitary waves manifests monotonic behavior for permissible range of obliqueness θ, whereas this scenario is acceptable to only width of double layers. The results are discussed in the context of

  14. Baryon-Strangeness Correlations in Au+Au Collisions at RHIC BES energies from UrQMD model

    CERN Document Server

    Yang, Zhenzhen; Mohanty, Bedangadas

    2016-01-01

    Fluctuations and correlations of conserved charges are sensitive observables for studying the QCD phase transition and critical point in high-energy heavy-ion collisions. We have studied the centrality and energy dependence of mixed-cumulants (up to fourth order) between net-baryon and net-strangeness in Au+Au collisions at $\\sqrt{s_{NN}}$= 7.7, 11.5, 19.6, 27, 39, 62.4, 200 GeV from UrQMD model. To compare with other theoretical calculations, we normalize these mixed-cumulants by various order cumulants of net-strangeness distributions. We found that the results obtained from UrQMD calculations are comparable with the results from Lattice QCD at low temperature and hadron resonance gas model. The ratios of mixed-cumulants ($R_{11}^{BS},R_{13}^{BS},R_{22}^{BS}$,$R_{31}^{BS}$) from UrQMD calculations show weak centrality dependence. However, the mixed-cumulant ratios $R_{11}^{BS}$ and $R_{31}^{BS}$ show strong increase at low energy, while the $R_{13}^{BS}$ snd $R_{22}^{BS}$ are similar at different energies. ...

  15. Collisions of electrons with hydrogen atoms I. Package outline and high energy code

    Science.gov (United States)

    Benda, Jakub; Houfek, Karel

    2014-11-01

    Being motivated by the applied researchers’ persisting need for accurate scattering data for the collisions of electrons with hydrogen atoms, we developed a computer package-Hex-that is designed to provide trustworthy results for all basic discrete and continuous processes within non-relativistic framework. The package consists of several computational modules that implement different methods, valid for specific energy regimes. Results of the modules are kept in a common database in the unified form of low-level scattering data (partial-wave T-matrices) and accessed by an interface program which is able to produce various derived quantities like e.g. differential and integral cross sections. This article is the first one of a series of articles that are concerned with the implementation and testing of the modules. Here we give an overview of their structure and present (a) the command-line interface program hex-db that can be also easily compiled into a derived code or used as a backend for a web-page form and (b) simple illustrative module specialized for high energies, hex-dwba, that implements distorted and plane wave Born approximation. Catalogue identifier: AETH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AETH_v1_0.html Program obtainable from: CPC Program library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data etc.: 30367 No. of bytes in distributed program, including test data etc.: 232032 Distribution format: tar.gz Programming language: C++11 Operating system: Any system with a C++11 compiler (e.g. GCC 4.8.1; tested on OpenSUSE 13.1 and Windows 8). RAM: Test run 3 MiB. CPC Library Classification: 2.4 Electron scattering External libraries:GSL [49], FFTW3[52], SQLite3 [46]. All of the libraries are open-source and maintained. Nature of problem: Extraction of derived (observable) quantities from partial

  16. Excitation and charge transfer in low-energy hydrogen atom collisions with neutral atoms: Theory, comparisons, and application to Ca

    CERN Document Server

    Barklem, Paul S

    2016-01-01

    A theoretical method for the estimation of cross sections and rates for excitation and charge transfer processes in low-energy hydrogen atom collisions with neutral atoms, based on an asymptotic two-electron model of ionic-covalent interactions in the neutral atom-hydrogen atom system, is presented. The calculation of potentials and non-adiabatic radial couplings using the method is demonstrated. The potentials are used together with the multi-channel Landau-Zener model to calculate cross sections and rate coefficients. The main feature of the method is that it employs asymptotically exact atomic wavefunctions, which can be determined from known atomic parameters. The method is applied to Li+H, Na+H, and Mg+H collisions, and the results compare well with existing detailed full-quantum calculations. The method is applied to the astrophysically important problem of Ca+H collisions, and rate coefficients are calculated for temperatures in the range 1000-20000 K.

  17. Hadronic rapidity spectra in heavy ion collisions at SPS and AGS energies in a quark combination model

    Institute of Scientific and Technical Information of China (English)

    SUN Le-Xue; WANG Rui-Qin; SONG Jun; SHAO Feng-Lan

    2012-01-01

    The quark combination mechanism of hadron production is applied to nucleus-nucleus collisions at the CERN Super Proton Synchrotron (SPS) and the BNL Alternating Gradient Synchrotron (AGS).The rapidity spectra of identified hadrons and their spectrum widths are studied.The data of π-,K±,φ,A,(A),Ξ- and Ξ+ at 80 and 40 A GeV,and in particular at 30 and 20 A GeV where the onset of deconfinement is suggested to happen,are consistently described by the quark combination model.However,at AGS 11.6 A GeV below the onset,the π±,K± and A spectra cannot be simultaneously explained,indicating the disappearance of the intrinsic correlation of their production in the constituent quark level.The collision-energy dependence of the rapidity spectrum widths of the constituent quarks,and the strangeness of the hot and dense quark matter produced in heavy ion collisions,are obtained and discussed.

  18. Search for Lepton Flavor Violation in ep Collisions at 300 GeV Center of Mass Energy

    CERN Document Server

    Abbiendi, G; Acosta, D; Adamczyk, L; Adamus, M; Amelung, C; An Shiz Hong; Anselmo, F; Antonioli, P; Arneodo, M; Ayad, R; Bacon, Trevor C; Badgett, W F; Bailey, D C; Bailey, D S; Bamberger, A; Barbagli, G; Barberis, E; Bari, G; Barreiro, F; Bashindzhagian, G L; Bashkirov, V; Basile, M; Bauerdick, L A T; Bednarek, B; Behrens, U; Beier, H; Bellagamba, L; Bénard, F; Bertolin, A; Bhadra, S; Bienlein, J K; Biltzinger, J; Bogusz, W; Bornheim, A; Borzemski, P; Boscherini, D; Botje, M; Breitweg, J; Briskin, G; Brkic, M; Bromley, J T; Brook, N H; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Bruni, P; Bulmahn, J; Burow, B D; Bussey, P J; Butterworth, Ian; Butterworth, J M; Bylsma, B; Caldwell, A; Campbell-Robson, S; Capua, M; Cara Romeo, G; Cardy, M L; Carlin, R; Cartiglia, N; Cases, G; Cashmore, R J; Cassidy, A; Castellini, G; Catterall, C D; Chapin, D; Chiba, M; Chlebana, F; Cho, G H; Chwastowski, J; Ciborowski, J; Cifarelli, Luisa; Cindolo, F; Cirio, R; Cloth, P; Coldewey, C; Contin, A; Cooper-Sarkar, A M; Corradi, M; Corriveau, F; Costa, M; Cottingham, W N; Crittenden, J; Cross, R; D'Agostini, G; Dagan, S; Dal Corso, F; Dannemann, A; Dardo, M; Dasu, S; De Giorgi, M; De Pasquale, S; Deffner, R; Deppe, O; Derrick, M; Desler, K; Devenish, R C E; Doeker, T; Dolgoshein, B A; Dosselli, U; Doyle, A T; Drews, G; Dubbs, T; Dulinski, Z; Durkin, L S; Dyce, N; Eckert, M; Eisenberg, Y; Eisenhardt, S; Engelen, J; Ermolov, P F; Eskreys, Andrzej; Fagerstroem, C P; Feild, R G; Feld, L; Fernández, J P; Ferrero, M I; Filges, D; Flasinski, M; Fleck, J I; Foster, B; Foudas, C; Frey, A; Frisken, W R; Gajewski, J; Gallo, E; Garfagnini, A; Geerts, M; George, S; Gialas, I; Gilkinson, D J; Gilmore, J; Ginsburg, C M; Giusti, P; Gladilin, L K; Glasman, C; Golubkov, Yu A; Göttlicher, P; Grabosch, H J; Graciani, R; Grosse-, J; Grothe, M; Grzelak, G; Haas, T; Hagge, L; Hain, W; Hamatsu, R; Hanna, D S; Harnew, N; Harris, V L; Hart, J C; Hartmann, H; Hartmann, J; Hartner, G F; Hasell, D; Hayes, M E; Heath, G P; Heath, H F; Heinloth, K; Heinz, L; Hernández, J M; Hervás, L; Hessling, H; Heusch, C A; Hilger, E; Hirose, T; Hochman, D; Holm, U; Homma, K; Horstmann, D; Howell, G; Hung, B H Y; Hung, L W; Iacobucci, G; Iannotti, L; Iga, Y; Inuzuka, M; Ishii, T; Jakob, H P; Jakubowski, Z; Jelen, K; Jing, Z; Johnson, K F; Jones, T W; Joo, K K; Joos, P; Karshon, U; Kartik, S; Kasemann, M; Kasprzak, M; Katz, U F; Kaziewicz, P B; Khakzad, M; Kim, C L; Kim, H J; Kisielewska, D; Kitamura, S; Klanner, Robert; Ko, B J; Kobrin, V D; Koch, W; Kooijman, P; Korzhavina, I A; Kotanski, A; Kötz, U; Kowalski, H; Kowalski, T; Krakauer, D; Kruse, A; Krzyzanowski, M; Kuze, M; Kuzmin, V A; Labarga, L; Labs, J; Ladage, A; Lamberti, L; Lancaster, M; Lane, J B; Laurenti, G; Lee, S B; Lev, G M; Levi, G; Levy, A; Li, C; Lim, J N; Limentani, S; Lindemann, L; Ling, T Y; Liu, W; Lockman, W; Löhr, B; Lohrmann, E; Long, K R; Loveless, R J; Loewe, M; Lu, B; Lüke, D; Lukina, O Yu; Maccarrone, G; Magill, S; Mainusch, J; Mallik, U; Manczak, O; Margotti, A; Mari, S M; Marini, G; Martin, J F; Martínez, M; Mas--, T; Maselli, S; Matsushita, T; Matthews, C G; Mattingly, M C K; Mattingly, S E K; McCubbin, N A; McFall, J D; McNeil, R R; Mengel, S; Metcalf, W; Meyer, A; Mikunas, D; Milewski, J; Miller, D B; Mine, S; Mo, L W; Monteiro, T; Morandin, M; Muchorowski, K; Mur, W N; Musgrave, B; Nadendla, V K; Nakao, M; Nam, S W; Nania, R; Nath, C; Ng, J S T; Nigro, A; Notz, D; Nowak, R J; Noyes, V A; Nylander, P; Ochs, A; Oh, B Y; Ohrenberg, K; Okrasinski, J R; Orr, R S; Palmonari, F; Park, H S; Park, I H; Park, S K; Parsons, J A; Patel, P M; Paul, E; Pavel, N; Pawlak, J M; Pelfer, Pier Giovanni; Peroni, C; Pesci, A; Pfeiffer, M; Piccioni, D; Piotrzkowski, K; Poelz, G; Polenz, S; Polini, A; Posocco, M; Prinias, A; Proskuryakov, A S; Przybycien, M B; Puga, J; Quadt, A; Rahn, J T; Reeder, D D; Rembser, C; Repond, J; Revel, D; Ritz, S; Riveline, M; Roco, M T; Roff, D G; Rohde, M; Roldán, J; Romanowsky, T A; Rulikowska-Zarebska, E; Sacchi, R; Sadrozinski, H F W; Sampson, C R; Sartorelli, G; Saunders, R L; Savin, A A; Saxon, D H; Schioppa, M; Schlenstedt, S; Schmidke, W B; Schneekloth, U; Schott, W; Schramm, D; Schulz, W; Schwarzer, O; Sciulli, F; Sedgbeer, J K; Seiden, A; Seifert, R J; Selonke, F; Shah, T P; Shche-, L M; Shulman, J; Sideris, D; Silverstein, S; Simmons, D; Sinclair, L E; Sinkus, R; Smith, W H; Solano, A; Solomin, A N; Saint-Laurent, M G; Staiano, A; Stairs, D G; Stamm, J; Stanco, L; Stanek, R; Stifutkin, A; Straub, P B; Strick, E; Stroili, R; Surrow, B; Susinno, G; Suszycki, L; Sutton, M R; Suzuki, I; Talaga, R L; Tapper, R J; Tassi, E; Terron, J; Teuscher, R; Tickner, J R; Tiecke, H G; Tokushuku, K; Trefzger, T; Tsurugai, T; Tymieniecka, T; Uijter--, H; Ullmann, R; Umemori, K; Utley, M L; Vaiciulis, A W; Van Hook, M; Verkerke, W; Voci, C; Voss, T; Vossebeld, Joost Herman; Votano, L; Vreeswijk, M; Wai, L; Walczak, R; Walenta, Albert H; Wang, M Z; Wang, S M; Waters, D S; Waugh, R; Wedemeyer, R; Westphal, D; Whitfield, A F; Whitmore, J J; Wick, K; Wiggers, L; Williams, D C; Wills, H H; Wilson, A S; Wilson, F F; Wodarczyk, M; Wolf, G; Wölfle, S; Wollmer, U; Wróblewski, A K; Wu, J T; Yamada, S; Yamauchi, K; Yamazaki, Y; Yang, S; Yip, T; Yoshida, R; Youngman, C; Za, J A; Zacek, G; Zachara, M; Zajac, J; Zamora Garcia, Y; Zawiejski, L; Zer-Zion, D; Zetsche, F; Zeuner, W; Zhang, H; Zhu, Q; Zichichi, Antonino; Zotov, N P; Zuin, F; De Kamps, M; De Trocóniz, J F; De Wolf, E; Del Peso, J; Van Sighem, A; Van Woudenberg, R

    1997-01-01

    Using the ZEUS detector at the HERA electron-proton collider, we have searched for lepton flavor violation in ep collisions at a center-of-mass energy s^1/2 of 300 GeV. Events of the type e + p -> lepton + X with a final-state lepton (mu or tau) of high transverse momentum, were sought. No evidence was found for lepton flavor violation in the combined 1993 and 1994 data samples, for which the integrated luminosities were 0.84 pb^-1 for e- p collisions and 2.94 pb^-1 for e+ p collisions. Limits on coupling vs. mass are provided for leptoquarks and R-parity violating squarks. For flavor violating couplings of electromagnetic strength, we set 95% confidence level lower limits on leptoquark masses between 207 GeV and 272 GeV, depending on the leptoquark species and final-state lepton. For leptoquark masses larger than 300 GeV, limits on flavor-changing couplings are determined, many of which supersede prior limits from rare decay processes.

  19. Light-by-light scattering in ultraperipheral Pb-Pb collisions at energies available at the CERN Large Hadron Collider

    Science.gov (United States)

    Kłusek-Gawenda, Mariola; Lebiedowicz, Piotr; Szczurek, Antoni

    2016-04-01

    We calculate cross sections for diphoton production in (semi)exclusive PbPb collisions, relevant for the CERN Large Hadron Collider (LHC). The calculation is based on the equivalent photon approximation in the impact parameter space. The cross sections for the elementary γ γ →γ γ subprocess are calculated including two different mechanisms. We take into account box diagrams with leptons and quarks in the loops. In addition, we consider a vector-meson dominance (VDM-Regge) contribution with virtual intermediate hadronic (vector-like) excitations of the photons. We get measurable cross sections in PbPb collisions. This opens a possibility to study the γ γ →γ γ (quasi)elastic scattering at the LHC. We present many interesting differential distributions which could be measured by the ALICE, CMS, or ATLAS Collaborations at the LHC. We study whether a separation or identification of different components (boxes, VDM-Regge) is possible. We find that the cross section for elastic γ γ scattering could be measured in the heavy-ion collisions for subprocess energies smaller than Wγ γ≈15 -20 GeV.

  20. Ion-polycyclic aromatic hydrocarbon collisions: kinetic energy releases for specific fragmentation channels

    NARCIS (Netherlands)

    Reitsma, G.; Zettergren, H.; Boschman, L.; Bodewits, E.; Hoekstra, R.; Schlathölter, T.

    2013-01-01

    We report on 30 keV He2 + collisions with naphthalene (C10H8) molecules, which leads to very extensive fragmentation. To unravel such complex fragmentation patterns, we designed and constructed an experimental setup, which allows for the determination of the full momentum vector by measuring charged

  1. Ion-polycyclic aromatic hydrocarbon collisions: kinetic energy releases for specific fragmentation channels

    NARCIS (Netherlands)

    Reitsma, Geert; Zettergren, H.; Boschman, Leon; Bodewits, Erwin; Hoekstra, R.; Schlathölter, Thomas

    2013-01-01

    We report on 30 keV He2+ collisions with naphthalene (C10H8) molecules, which leads to very extensive fragmentation. To unravel such complex fragmentation patterns, we designed and constructed an experimental setup, which allows for the determination of the full momentum vector by measuring charged

  2. Partonic Equations of State in High-Energy Nuclear Collisions atRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Nu

    2006-10-01

    The authors discuss the recent results on equation of state for partonic matter created at RHIC. Issues of partonic collectivity for multi-strange hadrons and J/{psi} from Au + Au collisions at {radical}s{sub NN} = 200 GeV are the focus of this paper.

  3. Jets in d(p)-A Collisions: Color Transparency or Energy Conservation

    CERN Document Server

    Kordell, Michael

    2016-01-01

    The production of jets, and high momentum hadrons from jets, produced in deuteron ($d$)-$Au$ collisions at the relativistic heavy-ion collider (RHIC) and proton ($p$)-$Pb$ collisions at the large hadron collider (LHC) are studied as a function of centrality, a measure of the impact parameter of the collision. A modified version of the event generator PYTHIA, widely used to simulate $p$-$p$ collisions, is used in conjunction with a nuclear Monte-Carlo event generator which simulates the locations of the nucleons within a large nucleus. We demonstrate how events with a hard jet may be simulated, in such a way that the parton distribution function of the projectile is frozen during its interaction with the extended nucleus. Using our approach, we demonstrate that the puzzling enhancement seen in peripheral events at RHIC and the LHC, as well as the suppression seen in central events at the LHC are mainly due to mis-binning of central and semi-central events, containing a jet, as peripheral events. This occurs du...

  4. Heavy ion reaction measurements with the EOS TPC (looking for central collisions with missing energy)

    Energy Technology Data Exchange (ETDEWEB)

    Wieman, H.H.; EOS Collaboration

    1994-05-01

    The EOS TPC was constructed for complete event measurement of heavy ion collisions at the Bevalac. We report here on the TPC design and some preliminary measurements of conserved event quantities such as total invariant mass, total momentum, total A and Z.

  5. The energy loss effect of incoming gluon from $J/\\psi$ production in p-A collisions

    CERN Document Server

    Song, Li-Hua; Duan, Chun-Gui

    2016-01-01

    The energy loss effect of incoming gluon from $J/\\psi$ production in p-A (or d-A) collisions is investigated by means of the E866, RHIC and LHC experimental data. The gluon mean energy loss per unit path length $dE/dL = 2.18\\pm0.14$ GeV/fm is extracted by fitting the E866 experimental data for $J/\\psi$ production cross section ratios $R_{W(Fe)/Be}(x_{F})$. The obtained result indicates that the incoming gluons lose more energy than the incident quarks. By comparing the theoretical results with E866, RHIC, and LHC experimental data, it is found that the nuclear suppression due to the incident gluon (quark) energy loss reduces (increases) with the increase of the kinematic variable $x_{F}$ (or $y$). The energy loss effect of incoming gluon plays an important role on the suppression of $J/\\psi$ production in a wide energy range from $\\sqrt{s}=38.7$ GeV to $\\sqrt{s}=5.0$ TeV, and the influence of incident quark energy loss can be ignored for high energy(such as at RHIC and LHC energy).

  6. The impact of energy conservation in transport models on the π−/π+ multiplicity ratio in heavy-ion collisions and the symmetry energy

    Directory of Open Access Journals (Sweden)

    M.D. Cozma

    2016-02-01

    Full Text Available The charged pion multiplicity ratio in intermediate energy central heavy-ion collisions has been proposed as a suitable observable to constrain the high density dependence of the isovector part of the equation of state. A comparison of various transport model predictions with existing experimental data has led, however, to contradictory results. Using an upgraded version of the Tübingen QMD transport model, which allows the conservation of energy at a local or global level by accounting for the potential energy of hadrons in two-body collisions and leading thus to particle production threshold shifts, we demonstrate that compatible constraints for the symmetry energy stiffness can be extracted from pion multiplicity and elliptic flow observables. However, pion multiplicities and ratios are proven to be highly sensitive to the yet unknown isovector part of the in-medium Δ(1232 potential which hinders, at present, the extraction of meaningful information on the high density dependence of the symmetry energy. A solution to this problem together with the inclusion of contributions presently neglected, such as in-medium pion potentials and retardation effects, are needed for a final verdict on this topic.

  7. Isospin effects of the Skyrme potential and the momentum dependent interaction at intermediate energy heavy ion collisions

    Institute of Scientific and Technical Information of China (English)

    GUO Wen-Jun; LIU Jian-Ye

    2008-01-01

    We improve the isospin dependent quantum molecular dynamical model by including isospin effects in the Skyrme potential and the momentum dependent interaction to obtain an isospin dependent Skyrme potential and an isospin dependent momentum interaction. We investigate the isospin effects of Skyrme potential and momentum dependent interaction on the isospin fractionation ratio and the dynamical mechanism in intermediate energy heavy ion collisions. It is found that the isospin dependent Skyrme potential and the isospin dependent momentum interaction produce some important isospin effects in the isospin fractionation ratio.

  8. Space and Time pattern of mid-velocity IMF emission in peripheral heavy-ion collisions at Fermi energies

    CERN Document Server

    Piantelli, S; Poggi, G; Bini, M; Casini, G; Maurenzig, P R; Olmi, A; Pasquali, G; Stefanini, A A; Taccetti, N

    2001-01-01

    The emission pattern in the V_perp - V_par plane of Intermediate Mass Fragments with Z=3-7 (IMF) has been studied in the collision 116Sn + 93Nb at 29.5 AMeV as a function of the Total Kinetic Energy Loss of the reaction. This pattern shows that for peripheral reactions most of IMF's are emitted at mid-velocity. Coulomb trajectory calculations demonstrate that these IMF's are produced in the early stages of the reaction and shed light on geometrical details of these emissions, suggesting that the IMF's originate both from the neck and the surface of the interacting nuclei.

  9. On production $e^{+}+e^{-}$-pairs by a high energy photon in collision with photons of a laser wave

    CERN Document Server

    Galynsky, M V; Galynskii, Mikhail; Sikach, Sergei

    1998-01-01

    We calculate the number of $e^+ e^-$-pairs produced by a Compton high energy photon in turn formed in the process $e + n \\gamma_0 -> e + \\gamma$ at simultaneous collision with several photons $\\gamma_0$ of the same laser beam initial electron beam and laser photons are helicity is considered. It is shown that taking into account nonlinear effects in the Compton backscattering leads to decreasing the threshold of production of $e^+ e^-$-pairs and increasing their number. The consideration is based on the direct calculation of matrix elements in the formalism of diagonal spin basis.

  10. Double-electron detachment cross sections in intermediate-energy H{sup {minus}} plus noble-gas collisions

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.S.; Fang, X.D.; Sen, A.; Matulioniene, R.; Kvale, T.J. [Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States)

    1995-07-01

    Absolute measurements of the total double-electron detachment (DED) cross sections for 3- to 50-keV H{sup {minus}} ions incident on helium atoms and for 5- to 50-keV H{sup {minus}} ions incident on neon and argon atoms are reported in this paper. The present DED cross sections are in better agreement with the previously reported DED cross sections for helium targets than for either neon or argon targets. A semiempirical calculation of the double detachment cross sections for the intermediate-energy collision region is also presented in this paper.

  11. Energy dependence of directed flow over a wide range of pseudorapidity in Au+Au collisions at RHIC

    CERN Document Server

    Back, B B; Ballintijn, M; Barton, D S; Betts, R R; Bickley, A A; Bindel, R; Budzanowski, A; Busza, W; Carroll, A; Chai, Z; Decowski, M P; García, E; Gburek, T; George, N; Gulbrandsen, K H; Gushue, S; Halliwell, C; Hamblen, J; Hauer, M; Heintzelman, G A; Henderson, C; Hofman, D J; Hollis, R S; Holynski, R; Holzman, B; Iordanova, A; Johnson, E; Kane, J L; Katzy, J; Khan, N; Kucewicz, W; Kulinich, P; Kuo, C M; Lin, W T; Manly, S; McLeod, D; Mignerey, A C; Nouicer, R; Olszewski, A; Pak, R; Park, I C; Pernegger, H; Reed, C; Remsberg, L P; Reuter, M; Roland, C; Roland, G; Rosenberg, L J; Sagerer, J; Sarin, P; Sawicki, P; Seals, H; Sedykh, I; Skulski, W; Smith, C E; Stankiewicz, M A; Steinberg, P; Stephans, G S F; Sukhanov, A; Tang, J L; Tonjes, M B; Trzupek, A; Vale, C; van Nieuwenhuizen, G J; Vaurynovich, S S; Verdier, R; Veres, G I; Wenger, E; Wolfs, F L H; Wosiek, B; Wozniak, K; Wuosmaa, A H; Wyslouch, B

    2006-01-01

    We report on measurements of directed flow as a function of pseudorapidity in Au+Au collisions at energies of $\\sqrt{s_{_{NN}}} =$ 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.

  12. Total cross sections for double-electron detachment in intermediate energy H{sup {minus}}+ neon collisions

    Energy Technology Data Exchange (ETDEWEB)

    Kvale, T.J.; Sen, A.; Fang, X. [Univ. of Toledo, OH (United States)] [and others

    1993-05-01

    Absolute total cross sections for the double electron detachment {sigma}{sub {minus}1,1} in collisions between H{sup {minus}} and Ne have been measured in the 5 - 50 keV energy range. A well-collimated H{sup {minus}} beam components of the collision products (i.e, H{sup O}, H{sup +} and H{sup {minus}}) are magnetically analyzed and directed into appropriately-biased Faraday cups for detection. The cross sections are determined by a quadratic least squares fit of the H{sup =} fraction as a function of the target thickness in the growth curve analysis of the data. The double-electron detachment cross sections increase monotonically with impact energy over the energy region covered in this experiment. The values of {sigma}{sub {minus}1,1} range from 1.02 x 10{sup {minus}17}cm{sup 2} at 5.0 keV to 5.54 x 10{sup {minus}17} cm{sup 2} at 50 keV.

  13. The Centrality Dependence of the Parton Bubble Model for high energy heavy ion collisions and fireball surface substructure at RHIC

    CERN Document Server

    Lindenbaum, S J

    2008-01-01

    In an earlier paper we developed a QCD inspired theoretical parton bubble model (PBM) for RHIC/LHC. The PBM quantitatively agreed with the strong charged particle pair correlations observed by the STAR collaboration at RHIC in the highest energy Au + Au central collisions, and also agreed with the Hanbury Brown and Twiss (HBT) observed small final state source size approximately 2f radii in the transverse momentum range above 0.8 GeV/c. The model assumed a substructure of a ring of localized adjoining 2f radius bubbles(gluonic hot spots) perpendicular to the collider beam direction, centered on the beam, at mid-rapidity and located on the expanding fireball surface of the Au + Au collisions. In this paper we extend the model (PBME) to include the changing development of bubbles with centrality from the most central region where bubbles are very important to the most peripheral where the bubbles are gone. Energy density is found to be related to bubble formation and as centrality decreases the maximum energy d...

  14. Properties of cylindrical and spherical heavy ion-acoustic solitary and shock structures in a multispecies plasma with superthermal electrons

    Science.gov (United States)

    Shah, M. G.; Rahman, M. M.; Hossen, M. R.; Mamun, A. A.

    2016-02-01

    A theoretical investigation on heavy ion-acoustic (HIA) solitary and shock structures has been accomplished in an unmagnetized multispecies plasma consisting of inertialess kappa-distributed superthermal electrons, Boltzmann light ions, and adiabatic positively charged inertial heavy ions. Using the reductive perturbation technique, the nonplanar (cylindrical and spherical) Kortewg-de Vries (KdV) and Burgers equations have been derived. The solitary and shock wave solutions of the KdV and Burgers equations, respectively, have been numerically analyzed. The effects of superthermality of electrons, adiabaticity of heavy ions, and nonplanar geometry, which noticeably modify the basic features (viz. polarity, amplitude, phase speed, etc.) of small but finite amplitude HIA solitary and shock structures, have been carefully investigated. The HIA solitary and shock structur